Document wrXo6Kpry5pz1nB2gNRBMnZyB

NIH Conference Current Concepts of Leukemia and Lymphoma: Etiology, pathogenesis, and Therapy Moderator: COSTAN W. BERARD, ivi.U Discussants: ROBERT C. GALLO, M.D.; EI-RINE S. JAFFE, M.D.; IRA GREEN, M.D.; a n d VINCENT T. DEVITA, JR., M.D.; Bcthesda, Maryland .., criltriar change (phenotypic) leading to leukeniia niay .~.,tYc a disorder of leukocyte maturation, but t h e etiologic ..+ctl~ar change (genotypic) remains unknown. W e present r. drnce hrre that human leukemic cells contain type-C ,.,IInformationand consider t h e possible significance of observation in the context of a working hypothesis. W e .,.,mniine reticuloendothelial neoplasms in t h e light of . .er cmmimologic, cytochemical, and ultrastructural -,thpdc for identifying cells of t h e T-lymphocytic, B,mphocytic, and monocyte-macrophage systems. Use of -.SC methods h a s led to a challenging concept of -rltpnant lymphomas a s neoplasms of various anatomic ,dfunctional compartments of t h e immune system. mtional studies, although still in their inception, have Srady provided provocative clues in t h e etiology and 3vthnphysiologyof these disorders. Advances in laboratory rsrarch have been paralled by dramatic changes in clinical wnlogy, as evidenced by trends in t h e treatment of tutc lymphocytic leukemia, acute myelogenous leukemia, dndukin's disease, and diffuse histiocytic lymphoma. )J ('OWAN W. ~ R A R D * :W e shall present a brief over- :? of rcccnt advances in the study of leukemia and ,-ilhrna. Our first speaker will discuss ideas on the ,lhoienesis and etiology of human leukemia. h~ Origin of the Lymphomas I)r. Rohert <'. G a l l o t : T h e r e is very little information ': thc causation of h u m a n lymphomas, except for Bur, u ' ~lymphoma. W e now have considerable evidence that IhL ilt's lymphoma is caused by an infectious DNA virus, ?r r p s t c i n - h r r virus. Final proof m a y depend upon a .. ' I l W Ilcmntnpntholopy Section, Lahorntory of PatholoRy. National mer Iwtiiiite. ' ( h i d . 1 ahnrntnry of Tumor Cell Biology. National Cancer Institute. I' 'n cditrd transcription of a Combined Clinical Staff Conference at the Ccnter, Rethesda, Maryland. 27 March 1975, by the National '''Crr Inctitiite and the National, Institute of Allergy and Infectious Qvps. National Institutes nf Health, U.S. Department of Health, Edu,"',n. a w l Welfare. "nak of Inlernsl Medicine 85351-366. 1976 specific therapeutic result. Since this subject has been reviewed recently by experts ( l ) , I will not discuss it further. Instead, I will focus o n o u r ideas on the origin of leukemias, especially acute myelogenous leukemia. Dinerent questions can b e asked about the origin of leukemias. Some relate to pathogenesis, that is, the physiologic abnormality and cellular change that leads to it-in short, the phenotypic change. Of concern to molecular biologists is the n a t u r e of the information responsible f o r the cellular change, the genotypic change (if any) responsible for the disease. PATI i o 0 EN PSIS Physiologic Change: Most workers believe that acute myelogenous leukemia results from a physiologic abnormality in the process of differentiation of the granulocyte precursors (myeloblasts) to the mature polymorphonuclear leukocytes o r between stem cells and committed granulocyte precursor cells. This is often viewed as a "block" in differentiation, and it has been discussed in detail (2-6). Studies from many laboratories have shown that substances are released into the medium from some cells and that, when added to hematopoietic cells, they can induce modest temporary growth and differentiation of these cells, especially o n a solid matrix. S u c h substances have been called colony stimulating activity and macrophage granulocyte inducer, and the assay systems for them were first developed by Sachs (7) and by Metcalf, Bradley, a n d Robinson ( 8 ) . T h e y seem to be heterogeneous, and those that have effects on human cells have not been chemically characterized. Some studies with these mate- rials have indicated that the phenotypic abnormality in acute myelogenous leukemia is reversible, that is, the cells respond to the putative regulator molecules and differenti- ate (7). Others believe that the arrest in differentiation, at least f o r most cells, is irreversible. T h e emerging hypothesis is that the population of leukemic cells is heterogeneous in the ability of the cells to respond (7, 9 ) , thus raising an important question: Is the genetic change (if a n y ) that leads to leukemic transformation present in 351 i' I' , only snnic of thc cells wc c:dl Iciikeniic, o r is it prcsent fiimilies with an extraordinary incidcnce of leukenlla, k in all cells. but expressed (IINA-.RNA) to a varying tlcgree in tlilTcrcnt Icuketitic cclls'! In either casc, these very high incidence of leukemia in an identical tul and other stutlics have shown that at least some oF the patient with leukemia. There are several theoretit., acute rnyclogcnart~ lcitkcmia rclls d o respond to thcsc sibilities by which hereditary abnormalities coitld stitiiuli. In addition. <;all:iglicr :in(! collcagites ( 10) re- ;in incressc in susceptibility to thc disease-for r \ ccntly discovered a new "f;icfor" that seeins to be com- plctely spccific for niyclogcnous Icukcmia cclls. This fac- tnr was ohtained from cnntlitioncrl mctlia from one par- ticular human einhrycwic ccll line. I t proniotes continuous cxponential growth of thrsc cells and niaturation o f at lc:~st sonic of tlieni i n liquid siispenrion culture. I t has no cllcct on ncutc or chronic lymphocytic Icrikeniia cells. nor- mal honc marrow, or normal peripheral hltrocl cc119. This factor diners from the colony stimulating activity in that or the other. [ I ] i t ic specific for leukemic cc11~.whcrcas colony stimu- lating activity works hcst or niorc predictably on normal lOlA.5 ON rlll NATURF OF 714E INFORMATION I P l \ o l \ t n cells; 121 it indtrces cxpoiicntid growth: 131 its eficrt can be niaintaincd continuoudy: nntl f"! i! w`,riis on cells i n IN I I l f K I hfO(il NFWS Chcn / nrtd < lnrs 2 Vtrrtrer. Viewed broadly, 1111re sit suspension and does not promote colony formation in the niany ~ : I I I ~ CoSf leukemia However, they may all IIIU~I~* agar plate system. The dilkrcncc between the rcsponses of the leukeniic and normal cells a p i t i emphasizes a cellular tlillerencc brtwccn thc two. Since sonic of these results wcre obtained with lcukeniic cclls containing marker chromosomcs :ind siiicc normal cellc do not rcspond to this factor, we belicve these rcsults srihstanti:tlly add to the one final common niolecular mechanism. Does i t tiivcd\c only derepression of normal iinaltered genes le;taltng 14 cells akin to the fetal state, o r does it invohc etm modification through change (mutation o r deletion t rv by ;icquisition of new information, as by infection? Most le~ikemogenicagents can causc genetic ch:inrc. h~ ,,.Lnf~ j .It, evidence that at lenst sonic acute myelngcnous Icukeniia cells can hc iritlriccd to clillcrcntiatr. Cellttlnr &/err (I'hruor,rpir.C`lrnrtgc): What is the precise wc do not know if this is essential f o r development 1x1 14t disc:tse. I describe below our ideas and some dat:i I I to these questions. ha 0, cellular change rcyx>risihlc for thcw functional diRcrcnccs betwccn normal and leukemic ccflc? Dcspitc many morpho- `Two major groups of viruses cause neoplasia in :mttn~h k; the D N A tumor viruses and the R N A tumor virriw R e logic, immunologic, and hiocheniical studies, this has nnt gnrding the leukemias, the accitmul;itcd data strowl! in. been pinpointed in acute niyclogcnous lcrtkeniia o r in any other neoplasia. For thenrctical reasons many workers suspect the mcnihrane. `The tlillcrcnces in the response of crimirt:cte the type-C R N A tumor viruses. Thew I iwd seem to have origiiiatcd from gene9 of normal cclk (I! I S ) . Some have rcmaincd under hast control :wd I? nornial and myelogenous Jecikcniic cells to the growthand dillcrentiation-itidllcing factors could also he viewed often cillletl endogcnorts. For scvcrat reasons. H'L` prrf:f thc lcrtii elms I type-C` virus ( 1 5 ) . We think infoiiiiatfiiln as differences in membrane recngnition of thcw factors. I lowevcr, by no incans are other mechanisms excluded. from thcsc viruses is involved in norinal d c v e l ~ y ~ ~ ~Y~ f l t (16. 17). and this might inclutlc the normal diflerctitifti~ Sachs (7) reported that murine leukemic and other trans- process of hem:itopoietic cells (17). When one hyiirldirfi formed cells respond dillcrently to certain lectins than do the R N A gcnonie of these viruses to DNA o f the twfnld normal cells, suggesting that the surface of transformed rinitifected host animal, an excellcnt match is o l i t i ~ d cells is altered. However, I ani not aw:ire of any sub- Althorigh dcrived from a given host cell, they arc ~ 1 ~ ~ stantial study of this with human leukcniic cells. I think not infectious for that ccll, a charactcristic that I,c\Y (1'' the best evidence that the surface of leukemic cells diflcrs has called xenotropic. There is no clear evidence Ih:lf from normal resides in the recent resultr of Rillings and viruws are oncogenic, at least not in their host, id l`crasaki ( 1 1 ) and particularly of Brown, Hogg, and belicve that, unless genetically altered. they arc nd Greaves ( 1 2 ) on isolation of a leukemic specific surface (Figure 1 ) . Some exilmples are RAV, of chickc.115, antigen. F A ( TORS INFI.VPNCING T i l l INC`IIJFNCE OF L E U K E M I A Several factors arc associated with an increase in the '*'endogenous mitrine viruses. RDI 14 of cats, the g~litlpaI"# endogenous virus, and the only endogenous vinic qb 'isolated from primates, the endogenous baboon fWT virus. I t could be argued that the AKR virus of lllice incidence of leukemia, and, since they are well known and endogenous. and it is leukemogenic. However, this antrnd often reviewed, 1 will mcntinii them only briefly: radiation, is inbred for high-incidence leukemia. Probably thr some chemicals (especially benzene), probably some anti- dogenous (class 1 ) "virogenes" of this animal have tumor agents. chloramphenicol, and certain congenital modified. We have proposed that if the class I e~W"nn` abnormalities often associated with chromosome abnor- "virogenes" are modified by mutation (heredity. Chcnril''k malities w c h as Down's syndrome and Bloom's syndrome, radiation, or by an infecting virus that can integrate ataxia telangiectasia, and Fanconi's aneniia. Heredity can into this region). this may lead to improper differen(lrtid also he very important; there arc several reports of and growth control (14). 352 September 1976 4 Annals of Internal Medicine Volume 85 Number 3 I , tyc tlcfinc a class 2 type-C virws as one that contains in h5 HE/\pcnomc at tcast some nucteotidc sequences de- Itcr;ll~lvdillercnt from its host ( I S ) . If a class l virus Isc,IpL~\ host control and hccomes infectious. it may un- prnctic change ( I S ) and heconie a cl:ts$ 2 virus for it, pltpiiial host. Or, if crivironmental events result in direct pncil,. change of the class 1 cndogcnous "virogene," and if II~Ssh..ould hc fully expressed (DNA-+RNA), then it lo1, \t,.ttld hccnmc ii c1;iqs 2 virus (Figiire 1 ). In this sense, the Clr ironnlenlal event would have caused the disease and elcl,I ~to Ivirus prodtiction. Jhwevcr, once formed, a class 2 til,$,. coiiltl triinvnit the leukemogenic information to ,,lheI ,ells, and in some instances it might become in- (15 and therchy he the natural primary cause of the ditr;i.s A clacs 2 virus is, in fact, iisually oncogenic and infccliutlq. <'lass 2 viruses can indeed he the natural infcrl,,tilscause of leukemia, as is often the case in cats 2nd ,~(.asionally seems to he the case in birds and at least in wilic priinatcs. l-he infection can be congenital (avian Iciilr~l~iao)r Iron, contact ( feline letikcniia ). T h e leukemia and \ Itcoma virrises of chickens, mice, cats, and primates arc c . iniplea of the class 2 viruses. Tahlc 1 summarizes ionic .,I the properties of these viruses. P/(,WIIP 7 y p r - C Virmc.s: Primate type-C viruses, class 1 2nd t 2, wcrc recently isolated. 'The hahoon cndogcnous Virw ..wmc lo he a typical class 1 virus (19). Man may a h Ivrhor a n cndogcnous class I virus (19), but, if so, it has 1iS.t yet hcen isolatcd. More importantly, a "family" of c l i w l b , related class 2 type-C viruses has hccn isolated friw .cvcrnl gibhon apcs and one woolly monkey (20, 11). '\,mie o f the gihhon isolntcs have conic from gibbons with Iwkcniin (ZO), and some can induce myelogenous lelrkci~iin ( 2 2 ) . The woolly isolnte (also called simian ~ ~ V I I v: iIrus) came from a fihrosarcomn. The gibbon EXPRESSION r--.--h7 II"*UI ~ F L C'VIRAL' O L N t S -----I---* CLASS I ENDODENOUS VIRUS IYFNOTAOPIC) GENOME MQDIFICA~IOH ON INrFCIIOLl CLASS I I I llEVERSF TRANSCRlPllON I INIiGR4 llON ENDOGENMK VIRUS IFCOl ROPIC) W O l r i ~ iC C ~ I .sYIRbL- OENrS ----c CLASSn '("'o'~llaY.cw"~~', OI L--------/ *mIIs l"rCCrl0W 1 EXOOENOUS vmus IONCOOENICI EXPRESSION '"&m 1. how they Smcahyemunadtlecrgilolugsternateitoinc mofodthifeicaotriiognin. of t y p d viruses and Shows class 1 Viruses gena prodtlcts and class 2 vlrusei 8s modifications of the 1 viruses. one consequence of which may be the aCqUlSltiOn oncoRW71ccapability. See text lor discussion. Table 1. Distlnguishing Features Betwwn Class 1 mnd Class 2 Typa.C RNA Tumor Viruses Class 1 Class 2 Source Usually normal tiswes; can he neoplastic tissues Oncogenicity Generally not known to be oncogenic Trancmission Usually vertical (germ line) as "provirus"; usually not infectious Molecular RNA gnome hybridization complexes Io DNA from uninfected cell Usunlly neoplastic tissues Generally known to be oncogenic Usually horiiontal but can infect germ line and can be vertically transmitted RNA genome complexes poorly lo DNA from uninfected cell virus can apparently he transmitted to other gibbons naturally (without inoculation) and can spread the diseaze*. Of great interest, most isolates have come from animals inoculated with human material. In a study in Thailand of 195 gibbons (23), 92 animals were injected directly with blood from human patients with malaria (or pawed from gibbon to gibbon). The remaining 103 animals were a control group. Most strikingly, 10 of the injected animals developed lciikemias or lymphosarcomas. The first isolates of the gihhon virus came from these animals. None of the 103 members of the control group developed neoplasia. The human blood may have in some way activated type-C virus already present in the gihhons. Alternatively, man may he the source of the virus. The woolly and gihbon isolates ate not endogenous to primates, and they may have had their origin in the distant past in mice, entering primates as an infectious and oncogenic virus (class 2 for primates) (24, 25). Evidoiice for Type-C Virus Cotiiportenrs iii firottait Lerrkeritia (Tnble 2): Several reportc have descrihed the presence of molecules in human leukemic cells relafed to analogous molecules of certain animal type-C viruses. They followed from the detection (26) and subsequent partial &rification (27-30) of a reverse transcriptase and of viralrelated nucleotide sequences (see below). Later reports (31, 32) dcscrihed detection of reverse transcriptase in virtually all patient9 with leukemia, including those in remission. This was done by the simultaneous detection assay (33), which measures a reverse transcriptnse-like activity and a high molecular weight RNA (hence virallike). Our results indicate a more restricted dicfribution. since we find the enzyme in only approximately 30% of patients with leukemia. However, for a positive score w e d o use this endogenous activity, but we also require partial purification and characterization of the enzyme. Use of the activity assay alone is, of course, more sensitive, but certainly the requirement for enzyme isolation and characterization gives added assurance that one is measuring reverse transcriptase. On the other hand, requirement ot enzyme isolation could lead to falw-negatives. A few years ago, Todaro and Gatlo (34) reported that in some cases of acute myelogenol~sleukemia the reverse __I-. KAwArru~T: Personal communlcatlon. Barrrd rt 81. * Leukamla and Lymphoma 353 , Table 2. Sunitnary of Evidence for 1ype.C Virus Relntcd Information colleagues ( 3 9 ) , studying leukemic: cells in shot, tVrm 1. in Some tiunian Leukemic Cells culture, reported transient release of viral-like p;ll~ic[n Vtral Related Conirwnent Reverse tranycriptase (hiochenlical) Rcvcrw tranrcriptace (iwnunch$c) 1'311 protein Viral-related nucleotide tequence hli~ccllaneoiisviral-related prntciiIc Itcteaw of virw or viruslike particlev References 2632, 33,44,47 20. 30, 34, 45 36 31, 32, 3c40. 126.' t P,41. ,42. 45-47 that contain RNA with sequences predominantly rc131p,l to the woolly monkey virus. Although the particle.; the described have not as yet heen shown to bud frcwi ceii niembranes nor to be biologically active, they represent release of immature viruslike particles prc, i,,ii~li identified within the cytoplasm of these cells (27.32. :',.IS, 40, 4 4 ) . Rcccntly, Nooter and co-workers (45) iu+iit,,I from a child with Icukeniic lymphosarcoma a vitti,, ih:,t apparently is also related t o the woolly monkey t,iru, Ciahelnian and associiites ( 4 6 ) isolated a similar viritj rrcrm transcript;iw is antigenically closely rc1;ited tcr the reverse a patient with chronic lymphocytic leukeniia, arid 1' I I I C ~ ~ traiir:riptnses of the gihhon ape leukcn1i:i and the woolly and colleagues ( 4 7 ) now report thnt they have iscrl.tid a rnonkcy sarconia viruses. Others (29, 30) later observed virus closely related to the woolly monkey virur-~~thhnll Ihic in several miire patients. I he reverse transcriptase ape virus "family" from several normal human cnr1~i)or that we havc itlentified in adult acute inyelogenous leukemia I f verified, this will he a landmark discovery. Aq merilioncd cells has conristently heen antigenically related to the above, in the woman with acute lilyclogenour lellLvn1i,i primate nncogcnic virurcs. This ha< not hccn the case in from whom we isolated the 141.23 virus, we later fiuind a other leukemias. Even in acute myelngenous leukemia our second virus cotnponent. In other studies, Panem iiiiil (tr- S I I C C C C ~has hecn limited to about 30% of cases. I n 1975, sociates also detected this second component, whii.li war Shrrr and Todaro (35) detected a polein antigenically closely related to the endogenous virur of bahoow. \Ye related to one of the major structural proteins (p30 recently detectcd the DNA provinls of the endnyrrout prntcin) of the same primate viruses, and Rolognesi, de- virus of bahoons in the spleen (received postmorteiii) 01 tccted viral-related proteins on the sitrface of lerikemic our patient ( 4 3 ) . This shows that the virus did i n fact cells. Otlicrs (31. 32, 36) found nucleic acids in the come from the patient and not from laboratory con. cytoplasm of leukemic cells that contained nucleotide tamination. sequences related to nioitse leukemia viruc RNA. We Since these viruses arc not truly endogenous hut i.ifher confirmed these results and extended them to show more class 2, we think the results of Panem and co-worker, (47) homology to the RNA nf the woolly monkey virus (37, suggest transmission from congenital infection. This o l u l d 3 8 ) . n recent finding of Mak and associates ( 3 9 ) and of explain the lack of epidemiologic evidence for infdian. Tavitiant: 7 hew results all say that information (complete since after congenital infection a virus may i m a i n or partial) related to genomes of animal type-C virus is dormant unless activated by an environmental stiilllflttc. piewit i n sonic and perhaps all human leukemias. AI- This idea is further supported by a striking clinic:il oh- thnugh there findiiigs do not bear on the origin of this servation by Thomas and colleagues ( 4 8 ) in %?afrlc.I:? infnrmation (cndopenour or acquired hy infection), the their now well-known reports. they descrihcd app:lrcnt detection in .wwitc cares of molecules related to class 2 leukemic transformation of normal donor hone-iwm u primate nnzogenic viruses suggests that in these the in- cells after inoculation into leukemic recipients. formation may have heen acquired. Baxt and Spiegel- One major problem to date with the viruses th:?f Ila'c inan ( 2 2 ) and Baxt ( 4 0 ) ohserved extra viral-related been isolated is that we have not yet regularly itiwlified .ieqrierices i n cells from all patients with leukemia that are a complete proviruq (the integrated D N A derived f r o m not wcn in normal cells. Further, these sequences are the virus after KNA-+DNA conversion) in hitmarl lcll. related to mouse leukemia virus. So far these very impor- kemic cellst. Even if all these observations are eorr('ct. (he tant results have not been confirmed. data from our results d o not indicate that this happ.nS In /soh/iort o/ 7 ' ~ p e - CVirits: Even though type-C virus all leukemias or even in all patients with acute myeloyl'lloll' infnrmation and components may be detected in some leukemia. Acqujsition of type-C viral information nw\' he leiikemiar. formation of whole virus nirist be rare, perhaps One of several means of causing leukemia by one m@lcclllar hccnuzc the virus may he defective o r suppressed. Recent- mechanism. ly, we identificd in a single patient type-C virus in two Dr. Costan W. Berard: Malignant lymph om^^ ha'' wparate blood samples and one hone marrow specimen traditionally been diagnosed and classified solely hy ohtnincd at three dilTerent periods in the coiirse of the morphologic criteria. Early classification schemes were disenrc (10. 41 ). The virus is infectious for many cells ( 4 2 ) a i d consirtz of two components---one closely related ____ t As noted nhove, D N A proviruv related lo the habnon rnd''~'""'" iypc-c virus was discovered in the DNA frnm postmnrtem w ~ l ~ " ' to the woolly monkey virus and the second closely related to the endogenoils type-C virus of baboons (41-43). We obtained from the wnman with acute myelo8ennus lerikemla (411 whme cella we Iwtated n type-C virus (IO. 41). Recently. WC f o l " " ~ ~ , ~ viriir rqiicnce$ of the hahoon cndogcnnus v l r i n in lhc DN* call thc virriz 111.23V. In the fresh, unciiltirred hkxx! a i l s uncultured t i w m from scvcr~~(lhut not all) other lcrikrmlc r~itimt' ( WoNa-SrrAi. F, GILLEIPIE D, GALta RC: Proviral reqiienceq of b,lh" (if this same patient, we found reverse transcriptase related endogenous type-c R N A V i N S in DNA or leuknemic t i ~ a t i c qI r l m 'r'c" lo the woolly monkey viruc ( 4 4 ) . In addition, Mak and psllents with nlyelnpenous leukaemla. Narvre, In prerr). The rrSl1li'Inn' cale (hat vlral niiclelc-acid sequencer related or ldentlcal 10 (h**c " . In the hnboon enclnpennar vlrug have heen acqiilred by some hunlay Bot nwrw 0 Pemonal communiralion. simples1 lntcrprclalion I s that of an interspeclet tranmisrion Of this t T ~ V I I I ~AN I'crwnsl cnmmunicallon 354 September 1976 -Annals of Intarnal Medicine Volume 85 In the past from baboon lo man. Number 3 -- llagll,w.~ith~ prohlems, largely because of diverse use of lenrlIt. terms such as "lymphosarcoma" and "reticulum ,rcoma" and lack of agreement regarding the cytologic ~enllllocf.~the neoplastic cells in many tumors. In the past J~(:~,I,, more detailed subclassifications of both Hodgkin's jitc.l ,. and the non-Hodgkin's lymphomas have been je\,.l, .ped and shown to have considerable value for .lirii .tpathologic stlldies (49). These new schemes, howo,cr. .Ire also hased primarily on morphologic criteria. \y,l/l Ihc advent of new immunologic, cytochemical. and ,Il~r:i irclctural techniques, it has been possible to chara c ! ~ ~n,otrLm~al cells of the T-lymphocytic, R-lymphocytic, Il;,,nocyte-macrophage systems. Recent application of [hc'c ,.me methods to the cells of letlkemias and malignant ~ ! ~ ~ i p ~ i 4ism laesading to dramatic advances in our underrl.lnriritg of the pathogenesis and pathophysiology of these di\,ri<l<,r(s5 0 ) . Doctor Jalfe will summarize present knowlL t ~ 1p ,~prding imnitlnologic markers on the cells of these IUI11111 . lrnniuuologic Markers I)r Elaine S. JalTe': Recent advances in immunology h v e I d to a reexamination of many of the conventional mnct ills regarding the classification and nomenclature of di\cn.,,s of the reticuloendothelial system. In the past, the vuall lymphocyte was regarded as an endstage cell, inrapnldt! of further maturation or division. We now know th.it 13 iih the appropriate stimulus, whether it he antigen, milown. or neoplasia per se, this cell can undergo a rn~trk.t,(l morphologic transformation and rapid cell division. Fiirllwrmore, the seemingly homogeneous population of ~ l : t I l lymphocytes seen in the peripheral blood and I!nlplt4l tissues in fact consists of at least two cell types, the '1 and R lymphocytes, with distinct origins. functions, and poperties (Table 3 ) . These cells, as well as a third d w r * f immunocompetent cells. the mononuclear phagoC!lc<, can be identified hy characteristic surface memhrane m d I . r c (Table 4 ) . These markers are most commonly idmlicd on cells in suspension isolated from either Perivlicral blood or lymphoid tissues. However, certain of {heir markers can be identified on cells in frozen tissue s e c l i l ~ l l ~s, pecifically receptors for complement, as shown hY t 1 1 ~Ihding of EAC (51, 5 2 ) , and receptors for cytophilic: antihody, as shown by the binding of JgG EA ( 5 2 ) . All these methods can be applied to normal as well as nenr':lstietissues for the identification of lymphoreticular cells Thrw immunocompetent cells have different localizallonr in- _the peripheral lymphoid organs, and, in fact, one * 9r4rinr~nverllpntor.llcmntopathoiosy SecUon, Laboratory of Pathol*Qv, N:llionnlCnnccr Institute. 'abla 3. Characterldlca of H u m a n B m d T Lymphocytes \ Origin "lhentiat ion runriion -4 B Lymphocyte Bone marrow Bursa equivalent; (?) liver khmoral immunity T Lymphocyte Bone marrow Thymus Cell-mediated immunity Tabla 4. Identification 01 Cells by Surface Markers. Slg C3 Fc E +T Lymphocyte + + + +B Lymphocyte Monocyte-histiocyte - f - *tf rtb $- t-- - - -s i 8 = membrane.bound sullnce immuno$.obudn: C3 receptor for third component of complemenl-commonly Identifled by binding of EAC (sheep erythrocytes coated with IrM and complcmeno: Fc = receptor lor Fc portlon of 1 1 0 identified by bindin# or IeOEA (sheep erylhm. cytcs coated with 110 antibody) or by binding of eggrelated fluorcscein- ated I&; E 3 spantanenus rosette lormallon with aheep erythrncylo; A8 = presence of specific iwanfinenr identifiable by preparation of spedRc antisera. t Receptor presenl only on a small population of activated T ceilr. t SI8 i s nof a cell product and i s nonspeciflcally bound. # Receptor present on pedphernl blood monocytes but not identified on all t i w x histiocytes. can view the anatomic compartments of a lymph node as the functional components of the immune system. B cells are distributed in the far cortex, the follicles and the medullary cords. However, B cells in these different sites differ with respect to both their function and their surface markers. The lymphoid follicle is a site of antigen localization ( 5 3 ) and also represents the proliferative arm of the B-cell system (54, 5 5 ) . The medullary cords, in which differentiation toward plasma cells occurs, comprise the secretory arm of the 9-cell system. The paracortex is the thymic-dependent portion of the lymph node ( 5 6 ) and the site of T-cell recirculation through postcapillary venules (57). Mononuclear phagocytes are distrihuted primarily in the cortical and medullary sinuses. Recent studies of the surface characteristics of neoplastic lymphoreticular cells have helped uq to understand how many of the malignant lymphomas relate to the above anatomic and functional components of the immune system (Figure 2 ) . 1 shall now discuss certain selected examples and show how each of the four major compartments manifests itself as neoplasia. Recent evidence indicates that nodular lymphomas are indeed neoplasms derived from the lymphoid follicles ( 5 8 . 5 9 ) . The Rappaport classification ( 6 0 ) , currently the most clinically relevant and widely used scheme, subdivider nodular lymphomas on the basis of the cytologic composition of the neoplastic nodules. The small cells are termed "lymphocytes" and the larger cells are called "histiocytes" hecause of their morphologic similarity to normal histiocytes. Studies at the National Institutes of Health ( 5 8 ) and at Vanderbilt University ( 5 9 ) have shown that all of these cells are in fact follicular B lymphocytes with identical patterns of immunologic markers, and that these different cell types probably represent different stages of transformation. The neoplastic cells are characterized by the presence of monoclonal surface immunoglobulin ( 5 9 ) and abundant complement receptors easily demonstrable on cells in suspension as well as in frozen tissue sections ( 5 8 ) . Nor- mal follicular R lymphocytes can also be distinguished from other B lymphocytes within a lymph node by the above surface characteristics. If nodulnr lymphoma represents the neoplastic equivalent of the lymphoid follicle, then well-differentiated lymphocytic lymphoma or chronic lymphocytic leukemia represents the neoplastic counterpart of the medullary cord Bererd et el. Leukemia and LymDhoma 355 Hod#klns O i ~ w . Figure 2. Diagrammatic representation of a normal lymph node, showing the anatomlc and functional compartments of the Immune system. The rnali#nsnt lymphomas are related conceptually and =functionally to each of the above compertments. S slnuset; F = follicles: PC z paracortcx: MC = medullary cords. R lymphocyte. These tumors never manifest a nodular growth pattern but always infiltrate in a diffuse fashion. I n well-differentiated lymphocytic lymphoma there is a proliferation of homogeneous, small, mature-appearing lymphocytes. These cells do not proliferate rapidly but are highly motile, like a mature lymphocyte, and readily gain access to the peripheral blood. Thus it is readily understandable that most patients with well-differentiated lymphocytic lymphoma are at great risk to develop chronic lymphocytic leukemia, and in fact these two diseases simply represent dilferent clinical expressions of the same neoplastic process. As expected, markers identified on the cells from welldifferentiated lymphocytic lymphoma and chronic lyniphocytic leukemia are identical. Studies in our laboratory of 10 cases of well-differentiated lymphocytic lymphoma and 13 cases of chronic lymphocytic leukemia have shown identical patterns of immunologic markers (61 ). These cells are characterized by the presence of monoclonal surface inmunoglohulin, most commonly of the IgM type; however, the staining is usually quite faint. This staining pattern contrasts with that of nodular lymphoma cells, is which bright fluorescent spots appear o n the cell membrane, often with spontaneous capping. The cells of welldifferentiated lymphocytic malignancies usually have complement receptors, another B-cell marker, but, in contrast to the cells of nodular lymphoma, their complement receptors are characteristically qualitatively or quantitatively deficient, such that they cannot be identified by the frozen section technique. This feature is also seen in the medullary cords, an area populated by plasma cells and lymphocytes presumably differentiating toward plasma cells. We have mentioned that the medullary cords comprise the secretory arm of the B-cell system. However, in most cases of chronic lymphocytic leukemia and well-differentiated lymphocytic lymphoma. secretion does not occur, and, in fact. hypogammaglobulinemia is observed (62). If in a lymphoma of this rystcm the immunoglobulin moiety is synthesized and secreted into the serum instead of being expressed only on the cell membrane, the patient u1 have a monoclonal gammopathy, most commonly of I g M type, and the clinical picture of WaIdrn\lr,irnl macroglobulinemia. in this event, the cells usuall) apppru more plasmacytoid. We turn now to tumors that appear to be of T-CVII! ~ , such as childhood lymphosarcoma or diliuse 1!mrb blastic lymphoma occurring in children and young :,dall, The presence of a mediastinal mass in many of pa. tients had suggested that these tumors might be ot l h y i origin (631, and in fact T-cell markers have hwn in a number of cases in vitro (64-66). As onc w o u ~ expect, these tumors also tend to involve the IIiymK. dependent portions of the lymphoreticular system (67 b, The large cell malignant lymphomas (reticuluirr cg, sarcomas) have been termed "histiocytic" in the Kappa. port classification because of their morphologic blance to normal histiocytes. However, immudogi studies of most cases of histiocytic lymphoma th:ir occw de novo show a heterogeneous pattern, sometimes ilcmon. strating B-cell markers (68-70), sometimes no tilarken (71), and, rarely, T-cell markers (70, 72). Presiiiinhly. these tumors are composed of highly transformed i v tlcdtl. ferentiated cells of diverse origins, and, because ( 4 this dedifferentiation, they fail to follow the homing pittertn characteristic of better differentiated lymphomas. hl.trken can consistently be shown in one group; namel). Ihmc cases in which the large cell tumor occurs as a propsctinn of k pervious neoplasm in which markers were pictcn!. t h e s e cases, when they occur as a progrcssion of chronic norni;ll :ipperritijt I. lymphocytic leukemia, are known as Richter's syndinme, from IIlidpkin's ti*.. and the cells retain the same surface imniunoglolvilin as recn 1.. be tightly ' the chronic lymphocytic leukemia cells (70). Thc tame Fltrthlvtnorc, thcw phenomenon can also happen as a progression of iiidular in: Ih.il they arr I' lymphoma, and, here again, B-cell matkers are rc1:iined lympli~icyte-Rerd.St (67). i d t n t i l i d hy scan. To turn to a neoplasm of true histiocytic origin. i i n b nalitrv 01 this intc one such example is well proven and that is r n a l t ~ l ~ ~ n lis ptruimably of p i histiocytosis, or histiocytic medullary reticulosis. I h i . dip 01bi\ disease. ease seems to represent a neoplastic transformatiotl the 1 h:we shown hi sintikoidal histiocytes of the lymphoreticular system. 1hcsc ccrmpivients of t hc cells retain the functional capacity of histiocytes and ha\c nopl.l.;ia. We hope a marked phagocytic potential commonly exhibitti1 a In iiiitlerstanci thc erythrophagocytosis. The cells also retain the imlllun* h p h w a s and wil logic mgrkers characteristic of histiocytes, showing re I h W i c s of this gror ceptors for cytophilic antibody (72). Dr costan W. i In Hodgkin's disease, application of these methods of win! ccll surface I identification requires a somewhat different apprtlach. I!nlph~wticrrhr ne( Most of the non-Hodgkin's malignant lyniphomas ~ l n s i c l functicwal cnmponc of a relatively homogeneous population of neoplastic cdlc* fificalion methods s but in Hodgkin's disease there is a population of neoPln5tic cell8 (the Reed-Sternberg cells and their mononuclear iants) admixed with a population that is presumed 1" reactive-lymphocytes, plasma cells, and eosinophils, "' have little direct information about the nature of the ked. Sternberg cell. However, much indirect evidence ~lb!@ that Hodgkin's disease involves the thymic-dependent Pop tiod of [he immune system. Early in the courJe 0'. Ihe disease, patients often manifest defects in cell-medlnted immunity (73). This disease is also seen to involve 356 September 1976 * Annals of Internal Msdlcln* Volume 88 Numbar 3 Table 5. 1-Cell Functions end Lymphokines T-Ccll Functions hlixed lymphocyte reactions Killer cells llclpcr cells for antibody formation Amplifier cells Suppressor cell? Site for spccilic recognition of the carrier portion or {lie antigcn Soluble Mediators of Cellular Immunity (Lyntphokines) Macrophage migration i!:I:ibh y factor Skin reactive factor Leukocyte inhihitory factor Lymphotoxin Osteoclast activation factor Chemotactic factor; blastogcnic factor; interferon; transfer factor; lymph node pernieabili1y factor other lymphomas, including Hodgkin's disease (87). Doctor BeFard has alluded to the significance ,)I cells, causing the attraction of a large number 01 cytes to the areas of erythroderma. However, whetll is the actual cause of the erythroderma or whetlac sponsible is not certain. Another test commoiily,used for a variety of 511 the so-called mixed lymphocyte reaction (88). ,111 malignancies with P X ~ I gal,,virus) can hc wed 11' e :, latent viral infertion with ihe cells that produce antibody, and cells that produce lyniptiokinins of various types that activate macrophages (78). Tnhle 5 outlines some of the known functions of T lymphocytes and some of the mediators produced by imnittnologically competent cells. I h e molecular basis for n i n n y of these functions is not understood, and the function? are dcfinecl by a variety of in-vitro assays. There are cells, for example, that kill various kinds of target crils. Some cells engage in mixed lymphocyte reactionsthat is, when one mixes together lymphocytes of two different persons, the lymphocytes undergo blast transformation. Some T cells interact with the B cells to produce antibody. Some cells suppress the function of others. Finally, T cells have receptors that recognize antigen and are presumably necessary for the initial aspects of antigen recognition. The nature of this receptor is still the subject of intense interest and controversy ( 7 9 ) . Some of the functions of these cells can be ascribed toa group of chemical substances called lymphokines (Table 5 ) . At least 25 different substances have been described, and some have been carefully defined. For example, macrophage migration inhibitory factor has been sophisticatedly isolated and identified ( 8 0 ) . Some of these other producls have not heen so carefully identified or defined nioleciilarly; these mediators of the immune response are produced by T cells, and some of them are also produced by cells or even by nonlymphoid cells (81). Some of these mediators are produced by abnormal malignant cells. An example of the production of these mediators by such cells is seen in Sezary's syndrome, a chranic form of leukemia characterized hy marked erythrodcrma. Although this is a rare disease, we were able to study five patients during the past 2 years and examine wnie of the products made by their cells. It should be noted that the malignant cell in this particular disease 4s thymiis-dcrived or a T lymphocyte (82, 83). whereas the lymphocyte of chronic lymphocytic leukemia is a B lymphocyte (84, 8 5 ) . Serum from these patients contains migration inhibitory factor for monocyte$. This factor can also be found in vitro by direct away of the lymphocytes from these paticnt9 (86). The serums and cells from normal control suhjccts show no such activity. However, this activi!y 5:s nlao been found in the serums of patients with various well with the survival of the allografts. The mixed 11 cyte reaction is also used to measure T-cell conip The reaction is mediated principally hy thymus d lymphocytes. When the lymphocytes of two noli general markedly deficient in their ability to respond the mixed lymphocyte reaction ( 8 2 ) . Also important is the fact that the neoplastic Ijiiip cytes of one of the patients with Gzary's syndront spheres of information 31 htc*6 summarizes Jam? ell. the detection of mar Iimphoid cells has helr serum and had a normal complement of H L A recognized and further supports evidence accu independent genetic means to suggest that antigcr,\ termined by another closely linked locus are resl*~1~1~ ccptotr or the idiatypic inin for the mixed lymphocyte reaction ( 9 0 ) . Th and study of homogeneous malignant cell pop provide insights into the normal workings of system. Another key point is that although patients with what diflerent spectrum of abnormality. Wh analysis of functional defects in the cells of will lead to information of clinical import seen. Functional studies and the studies discussed by Dr. Gallo have an intriguing connection; ther vocativt point$. Pint, of the lymphoid cell thought to be the etiological agent of Burki and infectious mononucleosis ( 9 1 ) . Neith cytes nor macrophages have this receptor. Fuflhermocr' the Burkitt lymphoma cells themselves are of the B lymphocyte ( 9 2 ) . Is this a coincidence? The importance of the Init 358 September 1976 9 Annals of Internal Mediclne Volume 85 Numbor 3 cc,,lid,i n the last 2 years a muririe virus has been de- bt,~. the Ahelson virus, which afttr injection produces extremely short latent periods of Tabk 6. Signiflcan& of Functional Studioa ' New methods of clakfication of lymphomas Aid in diagnosis, prognosis, and fdllow-up of elkcts of therapy Clonal populations of cells Identify products made by these cells, analysis of cell surface structure-provide clues as to function of normal cells Use in preparing specific antibodies Use in immunolopic studies such as mixed lymphocyte reaction and cellmediated lysis Pathophysiology of.diseasemay be explained by overproduction of lymphokines by malignant lymphocytes. for exampk, the erythroderma of Stzary's syndrome Surface receptors could also be r a p t o r s for virus-only B cells have receplors for Epstein-Barr virus Receptors or idiotypic immunoglobulins. or both, could be the target for highly specialized chemoimmune therapeutic attack crii,.inl because if tissues containing thymus-derived t r t l i l i I,, r c < ( , , , f 1 ( )i v.< I: ll:!!,llli !,I1 \ , , ; i i r :11v I , i f 11 ,h.I have discussed how these clonal populations ilisular lymphocytes for certain viruses. Finally. we t h t sometime i n the future we may use these re\ or the idiotypic immunoglobulins on the surface IIC of the cells. for example, in nodular lymphomas 11 chronic lymphocytic leukemia (96), as highly liwd targets for certain types of immunotherapeutic nce:liina reticuloendothelial neoplasms covered by the t h w discussants have emanated primarily from labo- ; t * : : , , : , ti,,l< 8 ~i'lll(- nr Vincent T. &Vita, Jr.+: I shall describe briefly I think are the trends in the treatment of four important diseases: acute lymphocytic leukemia of childhood, n1yelogenous leukemia of adults, Hodgkin's disease, dllTutehistiocytic lymphoma. The importance of the leukemias and lymphomas should n-nt.h_c llnderestimated In 1975 we apticipate 30 000 new cases of lymphoma (97). Furthermore, because these diseases affect a young population, their impact in terms of person-years lost in general or from the work force assumcs a greater importance than most other, even more common, malignancies. Actually, in the aggregate, the leukemias and lymphomas stand consistently fourth in morbidity and mortality rates in this country, behind such common killers as breast, lung, and colon cancer. ACUTE LYMPHOCYTIC LEUKEMIA OF CHILDHOOD It is now safe to sayithat we can cure a significant number of patients with acute lymphocytic leukemia of childhood. Survival is significantly greater among patients who receive the more aggressive modern treatment programs. Survival rates began to improve in the 1950s with the use of corticosteroids and the antimetabolite methotrexate. The impact of treatment programs was first felt with some intensity in the 1960s when combination chemotherapy p:sgrams came into force. Some of the early successful program were initiated here at the National Cancer Institute. It is important to emphasize that 25 years ago, in 1950, the median survival for patients with acute lymphocytic leukemia was 2% months. Almost all patients were dead within 1 year of diagnosis. Now, as 5-year survivals approach 5Ck% in some studies, median survivals hover between 3 and 5 years ( 9 8 ) . The increased survival has stemmed from the availability of many chemotherapeutic agents, each with independent activity, that could be used in combination), such as the four-drug V A M P and POMP programs (vincristine, methotrexate, 6-mercaptopurine and prednisone) introduced at the National Cancer Institute in the early 1960s by Dr. Freireich. Combination chemotherapy is now used to induce complete remissions (achievable in 95% of patients with little or no mortality) and for prolonged treatment after remission is achieved (consolidation therapy) to prevent relapse. With consolidation therapy, the duration of time a patient remains free of disease after all treatment is stopped has increased. Commensurate improvement in survival after cessation of therapy has been clearly shown. The use of the word "cure" is based on the flattening of the survival curves 5 years after treatment. When it was realized that the central nervous system is often involved in relapse in patients in bone marrow Sward or .I. Leukernla and Lymphorno 359 . -. r 0 60 c 0 c 8 050 2 a 21 8 0 BCGtCELLS MAINTENANCE 11 4 MTX 5-DAY MAINTENANCE 24 5 MTX BMI MAINTENANCE p r 0.5 0 10 6 12 18 24 30 36 42 48 Months Flgure 4. Survival of patients with acute lymphocytic leukemia In the National Cancer Institute series. MTX = methotrexate. remission, the concept of total therapy emerged. Data from St. Jude's Hospital i n Memphis, Tennessee, show the restilts of aggresqive reniission induction treatment, long consolidation therapy (in the studies cited for 2 to 3 years), and irradiation of the central nervous system plus the use of intrathecal niethotrcxate ( 9 9 ) . The survival of patients followed in recent studies can be extrapolated to the T-year point, and about half of these patients remain free of disease Similar retults have been achieved by the members of acute leukemia group E* and at the National Cancer Institute (100). The long-term, disease-free survival of patients in the National Cancer Jnstitute study is shown in Figure 4. The flat tails on the survival curves indicate a decreasing rate of relapse and risk of mortality after the first 2 years. Today, with 10-year follow-up data from older studies, we estimate that patients who are free of disease 5 years after i n t e n h e treatment have only about a 10% risk of developing recurrent leukemia. Ftirthermore, we can now segregate patients with acute lymphocytic leukemia into prognostic categories based on cell-surface markers. Patients with "null cell" disease have an excellent prognosis, whereas those whose lymphoblasts Rrc identifiahle as T cells, particularly those presenting with mediartinal tumors, have the worst prognosis. Future therapy will undoubtedly be tailored more and more to the aggressiveness of the disease, based in part on these cellular markers. Acute lymphocytic leukemia cells seem to be antigenic. -One would expect immunotherapy to be successful in _Mni L & N D IF. Personal commiinlcatlon rate is closely related to the age of the patients, er age 50 ( 1061. An lll,,,.l~t has raged in the literature for many years about .,l,,.r or not to treat acute myelogenous leukemia. I ,,l,;l~ly find the discussion somewhat specious, because ptienls who do achieve a complete remission, even ll ,,\,fertreatment programs, d o in fact have increased ,it )I free of disease. Those who d o not respond to ,,,,y do not live a shorter period of time than those not treated at all. The two most practical and \ U, and Clarkson (104) and the four-drug COAP r.illl reported by Whitecar and colleagues (see Refer- myelogenous leukemia than in acute lymphocytic St. Bartholomew's Hospital in London IS allogeneic cells after induction of re- '" a w myelogenous leukemia and in other diseases whete high remission rates are achieved but the relapse rate is `vhcre do we go from here in acute myelogenous leur remission induction and ions have been helpful, will not be without t interest is the pros- surface, or of enhancing the specificity of immunotherapy by Using the same ttpproach based on the work presented by Dr. Galla. HODGKIN'S DISEASE The results of treatment of this disease have been the most dramatic of perhaps any tumor studied in the past decade. Current data Suggest that 70% of all patients with Hodgkin's disease who walk in the door of a center studying this disease should be able to achieve a normal life span with either radiotherapy, chemotherapy, or radiotherapy and chemotherapy combined. The improved results can be traced to a better understanding of the pathology and natural history of the disease through staging laparotomy, technological advances in radiotherapy equipment and its use, and vastly improved chemotherapy program* <!12). It was recognized by Dr. Vera Peters in the early 1950s and by Dr. Eric Easson in the early 1960s that some patients with localized tumon treated with radiotherapy achieved normal life expectancy. Other radiotherapists, including Dr. Ralph Johnson at the National Cancer In- stitute and br. Henry Kaplan at Stanford University, rapidly expanded these observations. Doctor Kaplan ana- lyzed, from reports in the literature, the recurrence rate in treated fields, and he emphasized the marked dose-response effect between radiation dose and the ability to sterilize involved lymph node areas. He showed that patients seldom develop recurrences if the dose to a Aeld is more than 4000 reds ( 1 13). These observations and the realization that such doses could be safely delivered to large volumes of lymph node-bearing areas led physician* at both Stanford University and the National Cancer Institute to use what is now referred to as total nodal irradiation. At the National Cancer Institute, Johnson ( 114) randomized patients between the less aggressive extended-field radiotherapy and total nodal irradiation. The latter treatment proved superior in all patients except a subpopulation with nodular scleroshg t-fodgkin's disease, in which both treatments were equivalent. Overall, total nodal irradiation has proved superior to extended-field radiotherapy in patients staged withoWtbutine use of laparotomy and before the realization that today's more effective chemotherapy pro- grams may make less aegressive radiotherapy more ac- ceptable, because they can save those patients in whom disease recurs after radiotherapy alone. Our own contribution to this area wa9 the development of the MOP6 (nhrohen mustard, vincristine, procarbszine, and predhi4odb) folt-drug combination chemotherapy pro- gram, which increased the complete remission rate from 20% to 80% end markedly lengthened the duration of remission (from a median of 2 months to a median of 42 months) and durvival of patients with advanced Hodgkin's disease ( 1 15). Before MOPP therapy the median survival of patients with stbge It1 and I V Hodgkin's disease was consistently 2 y e a n or less. Less then 10% of patientr survived, and even fewer were free of disease after 5 years. In contrast, treatment with MOPP improved the 5-year survival to 70% (116). The survival curve of patients treated at the Nationat Cancer Institute has now reached h r r r d et d. Lwkernla and Lymphoma 361 j: *- . .. YfA.111 b 57 Figure 5. Survival of patients with advanced diffuse histlocytlc lymphoma i n the National Cancer Institute series 10 years. The diseuse-jree survival for the entire group of patients with stage 111 or IV disease who achieved complete remiscion is 50% at 10 years. It is crucial to examine these results by stage and histology. More than 90% of patients with stage lllA and IVA Hodgkin's disease had complete remissions, and, to date in our study, only one patient of those with stage l l l A and IVA disease has relapsed. Although patients in similar stages respond well to radiotherapy, the remarkable results of MOPP therapy woiild be difficult to improve on using radiotherapy or other combinations of drugs. The results are not as good in patients with stages IllB and IVB disease, in whom disease-free survivals range from 25% to 40% depending on thc histologic type. The variation in results by stage. the presence or absence of symptoms, a114rhe histologic type has caused some confusion in the interpretation of the literature. In contrast to the results with radiation therapy, nodular sclerosis histology adversely affects the diwaze-free survival rate in patients treated with MOPP. 7 hew results have been confirmed in a report from the Southwestern Cooperative Group ( 1 17) studying the effect? of maintenance MOPP treatment after remission induction This group showed a complete remiscion rate eqr ralent to the results from the National Cancer lnstitule, and a slight advantage for maintenance therapy with MOPP, when compared with the control group, in increasing the nuniber of patients remaining in complete remission A study from the National Cancer Institute (118). examining the same question but using a more intensive and prolonged induction period than in the Southwestern Group study, did not show a beneficial effect of maintenance treatment with either MOPP or BCNU (1,3 bis (2chloroethy1)-1-nitrosourea]when compared with a control population receiving no drug maintenance treatment. This question is still unresolved. A study from St. Bartholomew's Hospital in London, using a modified MOPP program in which vinblastine is substituted for vincristine, has shown similar results ( 1 19). Where d o we go from here in Hodgkin's disease? There are three trends. One is to combine irradiation therapy and drugr. attempting to use lesser amounts of irradiation than usually indicated in a given stage. Another trend is to develop a drug combination, not cross resistant with the MOPP program, to prevent relapse in patients who have a high risk of relapse after achieving a complete remission with MOPP. A third approach is to use immuno- therapy with or without chemotherapy as a form mission maintenance. Studies now in progress in institutions are examining all these questions. In a at Stanford, patients with stages I, 11, and IIE: dlsea and favorable histology (lymphocyte predominnlit a nodular sclerosis) are given mantle or involved-field radla4 tion therapy with six cycles of MOPP chemotherap, ad, the results are compared with those of a group rty,-lvlng only total nodal irradiation therapy. Patients WIIII un. favorable histology are given total nodal irradiaii,,n both cases, but one group receives six cycles of M o p p I , well. These studies should answer some very impod,,N questions, and the Anal results are eagerly awaitctt risk of carcinogenesis in using two such programs 4iould dampen the enthusiasm to use such approaches rotiiinely until enough data support them. In trying to develop a drug combination that is not cross resistant lo MOPP, Bonadonna and co-workers (120) used four drugs (adriamycin, bleomycin, vinblastine, a i d thc new imidazole derivative, dacarbazine), each individually active, to treat Hodgkin's disease and compared hi\ pro. gram with MOPP. The early results show a complcic re. mission rate equivalent to MOPP. Furthermore, thr earl) results also show that patients who fail on one piwram may benefit from the alternate treatment, suggesting that the two used in tandem might be effective in pre\ciiting relapses. Although other programs offering modifit d i m of MOPP-substituting a nitrosourea for nitrogen niwlard or adding bleomycin-or combinations using dillzrent schedules of the same drugs used in MOPP have .illown equivalent or even slightly better complete remission r ilec, none has as yet produced equivalent disease-free siii! ivalc ("cures"), and none fulfills the requirement of beiiil: lion. cross resistant to MOPP ( 1 2 1 ) . The preliminary da1.i thus far available on immunotherapy ( 1 2 2 ) are not yet wffi. cient to interpret accurately the role of immunotheiq) in this disease. Fifteen years ago Hodgkin's disease was treateti by radiation therapy for cure and by ineffective chemoflitslVY for palliation, and even efiective palliation was quertio~led r h e development of a single effective drug priwmm, MOPP, improved the lot of the patients with adwftcd disease who, at that time, did not usually receive efidive treatment With radiotherapy. fn addition, it gave rewrChers a neatly packaged therapeutic tool to balance with and against radiotherapy. The advantage of the MOW Pro' gram'is that it is now an old friend whose theraPJtic results and side effects are predictable. The emphasic in combinkd modality studies can now be on the inflllencc of the two treatments. irradiation and chemotherapy, On the natllfal history of the disease and not on an analysis of the details of the treatment program itself. MOPP produces a respectable cure rate and is therefore the logical drug program to use in combined modality tflalrs as in the Stanford study referred to above. It remains drug treatment of choice for stages 111 and 1V disease until other programs, now under study, ahcm equivalent disease-free survivals beyond the high-risk Poi"' of the survival curve ( 5 years) after all treatment stopped, or unless yther regimens producing equivalen' 362 Saptamber 1976 Annals of Internal Medlclnd Vo)ume 05 Number 9 I i,tlil, . I , ~significatttly easier to use. Itsp ittsTioc:Y ric LYM P H O M A I i,<,pethal the pathologists will tell us the true cell(s) pf rrli19it(ihistiocytes, reticulum cells, null cells, or maybe R <.c)i..)and whether this is one or many diseases. Using ,,,,,,itiied MOPF program in which cyclophosphamide is .!,i~,t,:~~tfcodr nitrogen mustard (C-MOPP), we have l:h;c..:,.J a 4 1 7'0 complcle remission rate in patients with lit and I V disease (122). The point worthy of re- p,*,l~r..~cnipha5is is that only one of the patients who a ~ h i%c, a complete remission has relapsed; the rest remain fn,.,.I discasc. None have been followed less than 3 years, ,il,,~ til< longcst survivor, now past 10 years from the end ,,ftr,,ttnicnt, remains free of disease (Figure 5 ) . As shown f~.!tlr.5c, everything that transpires in this disease does tt i:hin 2 years. Discase-free survival beyond 2 years, c ~ ~ : ~ ~ ,o~fi tchsesinitial stage of the disease or the type of trcnilitsnt, is tantaniount to cure. The only difference in \,irvis. ,,I curves gcncrated using radiotherapy for patients rlth 1,xalizcddisease (stage 11) and modern chemotherapy rroptnis for palients with advanced disease (stages 111 ;ind I\') is that the mcdian survival of patients with adv;lnc<!I disease is 6 months shorter. Similar results have now Iicen achieved by the group at Yale (123) using anoihci Ilrug combination. Ail iniportant aspect of the natural history of diffuse hi$"iig.i,.ytic lymphoma is that many patients present with wh:it wcms to be localized disease. However, the studies froni Stanford in which Jones and associates (124) used isvol\cd-ficld, extendcd-field, or total nodal irradiation \hcr:ipy show that patients with apparently localized dis- past fcspecially stage 11) d o not achieve good disease-free w r ? i ~ . l l (less than 30%) with radiotherapy alone no anllvr how aggressive the treatment. Staging lapamtnncy has not bccn helpful in this disease. Disease outside Ihc Iiiowti area of tumor involvement has been detected hy wrgcry in only a small numher of patients undergoing !his procedure (125); and yet the relapse rate of such patiwtc treated with local or extensive radiotherapy is very high. Since results with combined drug programs in Paliriils with advanced disease are as good as or better 'halt results with radiotherapy in localized disease, we have Inili;itcd studies ucing involved-field radiation therapy plus C-hIOPP or C-MOPP alone in patients with stage II disc ~ Ne. wer and, we hope, more effective drug combinah t c are being developed for patients with stages I l l and IV ifiscase. If1wnmary, dramatic advances have been made during the pact 10 years in our ability to control the diseases discll~wdabove. We should not lose sight of another very imPWant fact about the lyniphomas and leukemias. They w v e d as a slalking horse for the treatment of other 'U"km. The enthusiasm created by the use of combined motlalities In discascs such as Hodgkin's disease, which rWired close cooperation among three separate specialtiCs-radiotherapy, surgery. and medical oncology-has led Its to apply the same principles to the management Ot more common tumors, in some cases with con- siderable success. W'K&WW @k%m&'%:anrhnrc thnnk Mm. Psulmr Jtrhasz of the taborurory h h b p y ' W+wx*b Vwhw B~rWtc: *n4 Mg. Marian Segal of the Clinical Center for awilsnce 11) art preparation nf !his staff conference report. Received 11 May 1976;acccpted 23 June 1976. tRequests for reprints should be addressed to Costan W. Berard, M.D.;Head, Hematopathology Section, Lahoratory of Pathology, Notional Cancer Inctitute, Bldg. 10, Rm. 2A-09, National Institu?es of Health; Bethesda, M D 20014. References 1. zur HAUSEHN: Oncogenic herpes virusex Blochrm Eiophys Acta 417:25-53,1975 2. CLARKSON B. FNED 1: Changing concepts of IreaUncnt in acute leukemia. 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BERD D, CORNOOT, DECONTIRC,et ak: Long tetm remission in diffuse histiocytic lymphoma treated with combination ~ i i c l l i u l l l ~ l LdU~l l~l X, r 33: lUJU-lU34, I Y I 4 124. JONES SE, FUKS Z, KAPLANis, et ai: Non.lfrxlpCil lymphomas. V. Results of radiotherapy. Cancer 12:hf 691, 1973 125. CHABNERBA, JOHNSON RE, CHRETlEN PB, et al: Percnlanesi liver biopsy, peritoneoscopy and laparotomy: an asscwtw of relative merits in the lymphomata. Br I Cancer 11 (sui 2) :242-247. 1975 I- 366 September 1976 * Annals of Internal Madiclne * Volume 45 * Number 3