Document kVkM2nK6xdeOBpEdj7BRpmRb

Sarcomas at Sites of Subcutaneously Im planted Bakelite Disks in Rats By Floyd C. Turner, senior surgeon, National Cancer Institute, National Institute of Health, United States Public Health Service INTRODUCTION On November 6, 1936, a bakelite 1 disk, which had been coated with a very thin layer of 1, 2, 5, 6-dibenzanthracene by a vacuum distillation process, was implanted subcutaneously into the right side of an albino stock rat. An uncoated bakelite disk was implanted similarly into another albino rat, of undetermined origin, as a control. The test disk had been prepared by Dr. Egon Lorenz, of this Institute, for a study of the biological action of thin layers of carcinogenic hydrocarbons. Twenty days later the test disk was removed from the animal in order to observe the effect on the layer of hydrocarbon. No visible change was evident. The disk was not reimplantcd. This rat died without tu mor 11 months later, of cerebral abscess. The control rat bearing the uncoated bakelite disk was killed 23 months after the disk had been implanted. A tumor surrounding the bakelite disk measured 21 x 33 x 49 mm. Dr. Hugh Grady, of this Institute, examined the tumor and reported that it was-- an atypical fibrosarcoma composed of small bundles or nests of cells which varied from spindle to hizarre round or pear-shaped elements with large hyperchromatic tiuclei. There was a heavy network of collagen fibers closely attached to many of the tumor cells, and small numbers of irregular, poorly formed blood vessels were seen. In phosphotungstic acid haematoxyiin prepara- 1 Hak'ht' is format by the chemical vrteraction be tween. phenol and formaldehyde- In some products, a crude phenol, orlhoeicsal, is used, and in others, parafarm, a polymer of formaldehyde, is employed, As catalysts, the following, substances hare been used: caustic soda, sodium sidjile, kexamethylentclmmine, lactic acid, and glycerin. tions fibrogiia fibrils were identified in many tumor cells. Mitotic figures were numerous. Transplants of this tumor into two Wistar strain rats did not grow. Several investigators (7-3) have tested formaldehyde under varying conditions. None reported tumors following its use. No record was found to show that sodium sulfite, phenol, paraform, or orthocresol had been tested for tumor formation. Paracresol, which is chemically somewhat similar to orthocresol, was tested by Reimann (4), who made repeated applications to the skins of both rats and mice and observed no tumors after 6 weeks. Hexa methylenetetramine has been injected repeatedly into male mice by Dr. Shear and Dr. Stewart, of this Institute. 2 No tumors were observed in 5% months. Bogen and Loomis (5) observed one benign tumor after having painted the skins of white mice for more than a year with caustic soda. Twort and Fulton (6) made repeated applications of lactic acid to the skins of mice and observed no tumors in 25 weeks. Petroff and Krotkina (7) used nine rats into which they made injections into two sites. Into one site was implanted embryonic tissues, and into the other, em bryonic tissues plus lactic acid. Tumors occurred at the sites of the embryonic pulp, and in one rat a tumor arose at the site of the embryonic tissues plus lactic acid. Nakahara and Mori (8) fed glycerin to rats for more than 300 days. They ob served neither tumors nor any other significant pathological condition. Hence, 2 Shffir, Mo jf-f etml Stewart^ If. I,.: lishfd data. 81 Unpvh- SC-ELEC-00970 82 JOURNAI. OP THE NATIONAJ. CANCER INSTITUTE no very conclusive evidence of carcinogenic activiiv was obtained by any of the in gredients of bakelite, .by the methods re ported I.Xl'fiRI MfiXTAL 1`ROCKIU'Ri; F.xit.kimI.ni- 1 On October 4, 19$8, squares f bafccMte |f> x 10 x J}4 . were implanted sub cutaneously into the right sides of 10 male strain dba mice ZU month* old. The last [Hour' died at the age of 18 liiomhs. So (tiinors were observed in anv of the mice. I here was tm apparent rfianer on ihr suriarc of the bakelite squares. I.XI'fcRIMI-.M 2 On Dtmnhi'r ](>. 19.18, a bakelite disk was implanted stihrmancouslv into the right side of each of six male and six female \\ isiar strain rats 6 weeks old. The bakelite disks were In. mm. thick and 18 mm. in diameter. The surface of each disk had been removed with a new steel file tiller which the disks were scrubbed with a brush, soap, and hot water, rinsed in tap water, boiled in distilled water, and implanted. Several ut the rats died eatlv of pneu monia. 1 he first palpable mass at the 1'u.vhi. I.....Gross ,ip}H'4i.iu. i of tumor wliich developed around a bakelite disk. The other tumors had a similar appearance. I'tocHK 2.....Fibrosarroma showing bundles of spindle-shaped cells. Fhosphoumgstir at id barmatoxylin stain. X3M). site uf a bakelite disk teas observed 18 months after the disks had Iteen implanted, Right rats, live males and three female', were alive on that date. Of these eight rats, three developed tumors at the sites of the bakelite disks. The pathological diagnoses of these were also made by Dr. Grady. He found that- J all three tumors were fibrosarcomas and were; composed of interweaving (rands of tong, spindle*, shaped cells with tapering processes and darkly staining nuclei. Moderate amounts of collagen were present in two instances, while tu lire third tumor large collagenous bundles were observed, fibioglia fibiils weie easilv identified in all tmre tumors and mitotic figures were present. No attempt was made to transplant dte rumors (figs, 1 ami 2). In three tumors a brownisli-orangf'-coJori'd fluid was in con tact with the bakelite disk. In one instance, the disk was inclosed in a evst containing this fluid, ilistopaihologicslexnnunatkm of this fluid by Dr. Ga<fi SARCOMAS INDUCED BY IMPLANTED BAKELITE DISKS 83 revealed large numbers of mononuclear cells. A spectrographic examination of the fluid by Dr. Herbert Kahler, of this Institute, revealed only components of the hemoglobin spectrum. DISCUSSION Disks were implanted into 13 rats. Nine of the rats lived to be 20 months of age. or older; tumors developed in 4, 3 males and 1 female, Bakelite squares were implanted into 10 mice. Six of the mice lived to be 18 months old and had had the bakelite constantly in contact with their subcutaneous tissues for 15 months. This period of time was proba bly as great a fractional part of the life span as that experienced by the rats, yet tumors developed in the rats but not in the mice. Although the number of test animals was small, the findings suggest that the rats were more susceptible to tumor formation by this agent. What factors underlie this difference are not known; both were fed the same diet, dog chow, except that the rats were occasion ally given cod-liver oil because they showed evidence of vitamin A deficiency. This dietary deficiency was not studied in relation to tumor formation. A tumor, a mammary adenofibroma. developed at the base of the tail of the last surviving rat (female) which lived to be 26 months old. It probably was a spon taneous tumor which arose uninfluenced by the presence of the implanted disk. No tumor was found at the site of the bake lite disk. It required many months for the tumors to develop around the disks, but they grew rapidly after their initial appearance. There appeared to be very little, if any, erosion of the bakelite disks. The mode of action of the biological processes involved in the formation of tumors by bakelite is as ambiguous as the modus operandi of other carcinogenic agents. Although tumors occurred in the rats and not in the mice, chronic irritation cannot be entirely excluded as an adjuvant factor, for the subcutaneous tissues of the rat may be more favorable to tumor forma tion than the subcutaneous tissues of the strain of mice employed. The fact that all of the mice and most of the rats bore the disks continuously in con tact with their subcutaneous tissues for most of their entire lifetimes without de veloping tumors suggests a very lowhazard of carcinogenicity. SUMMARY Bakelite disks were implanted subcu taneously inlo 13 rats. Of 9 rals which survived longer than 20 months, 4 de veloped sarcomas at the site of the disk. REFERENCES (7) Gakschjn, W. G.: Uber die Bedcutung des exogenen Faktors in der Gcnesc der atypyischen Epithelwucherungen. Ztschr. f. Krcbsforsch., 45: 62-73 (1937). (2) Garschin, W. G., and Sckahao, I.. M.: Uber atypyische Wucherungcn des Bronchiaicpithels bei Einfiihrung von Formalin in das Lungengewebe. Ztschr. f. Krcbs forsch., 43: 137-143 (1936). (3) Orr, J. W.: Changes antecedent to tumour formation during treatment of mouse skin with carcinogenic hydrocarbons. J. Path. & Bact., 46: 495-515 (1938). (.'!) Reimann, S. P.: Proliferation of rat and mouse epithelium from sulphydryl. Protoplasma, 10: 82 (1930). (5) Bogen, ., and Loomis, R. N,: Comparative carcinogenic potency of common agents. California & West. Med., 43: 135 138 (1935). (if) Twort, C. C., and Fui.ton.J. XL: Further ex periments on carcinogenicity ol synthetic tars and their fractions, j. Path. & Ban.. 33: 119-143 (1930). (7) Petrofp, N. N., and Krotkina, N.: Grcfl'es embryonnaircs ct tuincurs malignes. Bull. Assoc. Irani; p. t'gtudc du cancer, 17: 566-589 (1928). (,<?) Nakahara, W., and Mori, K.: Preliminary note on production of cirrhotic changes in liver by furfural feeding. Proc. Imp. Acad., Japan, 15: 278-281 (1939).