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CHEST Official publication of the American C ollege of Chest Physicians Mesothelioma following Exposure to Asbestos: A Review of 72 Cases Maxwell Borow, Alfred Conston, Lawrence Livornese and Norbert Schalet Chest 1973;64;641-646 DOI 10.1378/chest.64.5.641 The online version of this article, along with updated information and services can be found online on the World Wide Web at: http://www.chestjournal.org/content/64/5/641.citation CHEST is the official journal of the American College of Chest Physicians. It has been published monthly since 1935. Copyright 1973 by the American College of Chest Physicians, 3300 Dundee Road, Northbrook, IL 60062. All rights reserved. No part of this article or PDF may be reproduced or distributed without the prior written permission of the copyright holder. (http://www.chestjournal.org/site/misc/reprints.xhtml) ISSN:0012-3692 Downloaded from www.chestjournal.org by guest on August 24, 2009 Copyright 1973, by the American College of Chest Physicians CRITICAL REVIEW Mesothelioma following Exposure to Asbestos: A Review of 72 Cases* Maxwell Borow, M.D., F.C.C.P.; Alfred Conston, M.D.; Lawrence Livornese, M.D., F.C.C.P.; and Norbert Schalet, M.D. alignant tumors arising in mesothelial tissue have been so rare that until recently they were considered pathologic curiosities. The reputed in cidence of primary mesothelioma has varied from .02 to 0.2 percent of all autopsies, with a ratio of 2:1 in favor of the man affected. In 1957, Wagner et al1 reported the first large series of patients with mesothelioma from the Cape of Good Hope asbestos fields in South Africa. By 1962, they had collected reports of 87 pleural and 2 peritoneal mesotheliomas.2 In all but two they1 could establish a history of exposure to asbestos dust from either industrial or environmental contact. Subsequently, there were reports of patients with this malignancy from other countries, and in almost every series there was a high association with expo sure to asbestos.3-7 In this country, Selikoff et al8 studied 307 con secutive deaths among asbestos installation workers and found 10 deaths caused by mesothelioma. In addition, they noted a high death rate attributed to other malignancies, particularly of the gastroin testinal tract. In 1967, our group9 reported 17 ^patients with mesothelioma, of which nine cases were pleural and the remainder, peritoneal. Since then, we have treated 36 additional cases, making a total of 53 patients. A search through the medical records of neighboring hospitals brought to light another 19 cases, making the total number 72. Fiftyone of these were pleural (71 percent) and 21 were peritoneal (29 percent). Sixty-four (89 percent) of these patients were men, and information of occupa tional exposure was present for all but nine, where no history was available. Eight of the patients were "From the Somerset Hospital Department of Medicine, Sur gery and Pathology, Somerville, N.J. Reprint requests: Dr. Borow, 515 Church Street, Bound Brook, New Jersey 08805 CHEST, VOL. 64, NO. 5, NOVEMBER, 1973 women, three of whom had a history of occupational exposure to asbestos, two had environmental expo sure to asbestos, and the remaining three had an inadequate history in their medical records. Of this group of 72 patients, there were 68 deaths with autopsies. Four are still living, but with disease. As has been documented before, our patients were exposed to asbestos 20 or more years before the malignancy appeared. Although most of these sub jects smoked two or more packs of cigarettes per day, three were nonsmokers. Apparently, the incidence of this malignancy is increasing. From 1951 to 1959 there was a total of only four cases. In the first half of the 1960's, the number of cases averaged one to four per year. In the second half, there was a noticeable increase up to eight or nine cases per year. Since this nearby asbestos mill has been in opera tion for half a century and has been the source of all of our case material, we wondered if there had been other cases of mesothelioma in which a correct diag nosis had not been made in earlier years. We re viewed all the autopsy records from 1948 to 1963 and found only two cases which now must be con sidered as mesothelioma. Inasmuch as it has been only a few years since the asbestos industry has instituted measures to reduce the incidence of pul monary asbestosis, we can expect to see increasing numbers of patients with mesothelioma for the next 20 to 30 years. Then, providing that these health measures are sufficient, there should be a dramatic reduction in the incidence of this malignancy. Clinical Featubes The period of exposure to asbestos is known in approxi mately 35 of our patients and reveals a wide rangfe. Most of these subjects worked from 15 to 35 years in the industry, with an average of 25 years. However, there were five 641 Downloaded from www.chestjoumal.org by guest on August 24, 2009 Copyright 1973, by the American College of Chest Physicians 642 patients with less than four years' exposure. Two of these, who were among the youngest patients in our series, 41 and 45 years old, were employed 10 months and 18 months, respectively. They both worked as stock boys, presumably in areas which were not heavily contaminated with asbestos dust. None of the patients who worked fewer than five years showed any radiographic evidence of pulmonary asbestosis. Our experience has been similar to others in that we have not seen mesothelioma develop simultaneously in more than one serous cavity, although in the later stage of the disease it often spreads to involve other cavities. Patients with pleural mesothelioma came to the hospital with mild chest pain or a varying degree of pleural effusion. In a few instances the chest pain was moderate to severe, signifying chest wall involvement by direct extension of the tumor. In addition to the pleural effusion or pleural thick ening only, there was a varying degree of pulmonary fibrosis. It has been an interesting observation that most patients with mesothelioma, whether pleural or peritoneal, do not have the extensive pulmonary fibrosis radiographically, as shown by those patients with cancer of the lung and asbestosis. Ap proximately one quarter of our patients with mesothelioma had completely normal findings on chest x-ray films. In many cases, the only clue to the presence of pulmonary asbestosis was the radiographic finding of a calcification on the dia phragmatic or parietal pleura. To many, the presence of these pleural plaques on a chest x-ray film suggests that the patient has been exposed to asbestos, even though other radiologic or clinical evidence or asbestosis is not present. In 50 percent of the cases, the pleural effusion was straw colored and in the remainder it was serosanguineous to markedly sanguineous. The initial diagnosis was made either by needle pleural biopsy and Pap smear or by exploratory thoracotomy and biopsy. In those patients subjected to ex ploratory thoracotomy, there was always a membrane of varying thickness on the lung which, depending upon the extent of the disease, was restrictive (Fig 1). The parietal pleura was also involved with a similar process, and in some cases the visceral and parietal pleura were intimately ad herent to one another and sometimes could not be separated. To the inexperienced, the process on the lung might appear to be an inflammatory membrane, and on several patients a decortication was in process until frozen section revealed the true nature of the disease. In most situations, decortication was difficult because of the intimacy between the mesothe lioma and the lung, although in some cases, the process peeled off without any air leaks. Patients with peritoneal mesothelioma sought medical at tention because of vague abdominal discomfort, weight loss, Figure 1. Pleural mesothelioma encasing lung. BOROW ET AL Figure 2. Peritoneal mesothelioma encasing loops of bowel. or distended abdomen. Most of these patients had ascites, and in a few, an ill-defined thickening of the abdominal wall could be felt on rectal examination. Laboratory workup, x-ray films of the gastrointestinal tract, and other studies were invariably unrevealing except for occasional external compression or rigidity of the large bowel, usually in the rectosigmoid area. The diagnosis was made by peritoneoscopy and biopsy or by exploratory laparotomy. The majority of patients with ascites were found to have small papillary projections studding the visceral and parietal peritoneum, as opposed to the more sheet like pleural appearance. A striking finding in almost every case was the appearance of the omentum, which was usually contracted, thickened, and most heavily diseased, even when the peritoneal surfaces showed minimal involvement. The ascitic fluid was usually straw colored, although in a few instances it had a syrupy consistency. In the later stages of this disease, the nodules have coalesced to produce large tumor masses, which eventually obliterate all the free space in the peritoneal cavity. The organs were found embedded in a solid mass of glistening tissue, which on cut surface usually had a mucinous appear ance (Fig 2). With this malignancy, there is rarely invasion of the organs. The growth remains on the surface, and by increasing in size, compresses the lungs or organs of the peritoneal cavity. In a few instances, metastatic disease was found at autopsy, mainly in the liver and regional lymph nodes. Whereas there can be a gross difference in appearance between peritoneal and pleural mesothelioma, this has not been true microscopically. Histologically, there are two major types of mesothelioma, and both have been found in the pleural and peritoneal locations. The more common variety is" the epithelial type in which there are cuboidal or polyhedral cells producing a tubulopapillary appearance or a solid group of cells without a clear tubular formation (Fig 3). Usually there is a fairly uniform cellular structure, but occasionally bizarre nucleated cells can be seen. The other variety is the mesenchymal or fibrous type of mesothelioma in which spin dle cells are arranged in an almost fascicular pattern without a stroma of abundant hyaline collagen (Fig 4). Occasionally, the cells may be arranged loosely in indistinct fasciculi or may occur in solid sheets. In many cases there is a mixed histologic appearance in any given area, and often a change from the epithelial to the mesodermal type in different parts of the same tumor. The tumor cells produce significant quantities of acid mucopolysaccharides, tending to confirm their origin from mesothelial tissue. This material can be assayed chemically in the fluid aspirate. It can also be CHEST, VOL. 64, NO. 5, NOVEMBER, 1973 Downloaded from www.chestjournal.org by guest on August 24, 2009 Copyright 1973, by the American College of Chest Physicians MESOTHELIOMA FOLLOWING EXPOSURE TO ASBESTOS 643 Figure 3. Tubulopapillary type mesothelioma. observed in tissue sections following appropriate histochemical staining. Clinical Course Initially, these patients show relatively few symptoms. In about half the cases, there is a fairly rapid reaccumulation of fluid. As the disease progresses, there is coalescence of the tumors with gradual compression of the organs, becoming more symptomatic five to nine months after diagnosis. The patients with pleural mesothelioma first notice their exercise tolerance decreasing, then develop a gradual progressive increase in dyspnea until they become bedridden as the anoxia increases. Death is essentially of suffocation unless a sudden catastrophe, such as inferior vena cava occlusion, occurs. Patients with peritoneal mesothelioma waste away as they, too, develop a progressive exercise intolerance, inanition and weight loss. Chemotherapy and radiation or combinations of modalities have not altered this course. Many of the patients, especially those with ascites, required very frequent aspirations, even though various therapeutic agents were instilled. As the peritoneal process continued, very distinct masses could be palpated, and eventually in some patients, these masses extended through the abdominal incision or the paracentesis site until they were subcutaneous in location. In general, the patients with peritoneal mesothelioma lived only a few months longer than those with the pleural process, but did so somewhat more comfortably. This difference is attributed to the ventilation perfusion problems that exist in patients with pleural disease. As the mesothelioma expands in the pleural Figure 4. Mesenchymal type mesothelioma. cavity, it compresses the lung, and although there is a decrease in pulmonary flow through that organ, a significant right-to-left venous-arterial shunt develops, which adds fur ther to the patient's anoxia. Since the malignancy extends to the opposite pleural cavity only late in the disease, it has been postulated that if the diseased lung should be removed, this venous-arterial admixture of blood could lie prevented. Accordingly, a recent patient, thought to have very local ized disease, was subjected to an extrapleural pneumonec tomy with pleurectomy, followed by intracavitary nitrogen mustard and cobalt radiation. However, three months later he had contralateral involvement and died five months from the time of diagnosis. This patient's rapid deterioration suggests several possibilities. One is that the pleura is a natural barrier for preventing the spread of this disease until late. Another consideration is that this patient had pre-existing involvement of all of his mesothelial tissues. It has also been our experi ence that pleurectomy to prevent the recurrence of effusion has actually lessened the longevity of these patients. Unlike the experience of Whitewell and Rawcliffe7 who have reported that 26 percent of their 52 patients with this disease lived over two years and one was still living after four years, our median survival has been 15-16 months, with none of our patients surviving over 19 months, with the exception of one patient who died 2!i years later. Our results are comparable to most other reported series of malignant meso thelioma. We treated patients with radiotherapy in combina tion with multichemotherapeutic agents, such as cyclo phosphamide (Cytoxan), nitrogen mustard, 5 flurouracil actinomycin D or radioactive materials. There was no evi dence of any amelioration of the disease other than occa sional relief from pleuritic pain. Therapy did not prolong the longevity of the patients. Because of the bleak outlook with current forms of therapy, we have begun a series of experi ments designed to test both a variety of chemotherapeutic agents as well as any immunologic aspects of this neoplasm. Fresh biopsy material has been supplied for both in vitro and in vivo culture. This work is being conducted by several agencies and will be the subject of a report at a later date. Discussion Selikoff,10 in conjunction with the Asbestos Worker's Union, has been observing approximately 600 employees who have worked at least 20 years in this particular asbestos mill, until 1959. Approxi mately 200 died, and of this number, 90 were ad mitted to our institution. From this group, there were 48 autopsies, and in 26 (55 percent) the pa tients were found to have some type of malignancy. Table 1 shows the distribution of these malignancies. Forty-two other patients from this group had major or minor surgical procedures, and 19 (45 percent) were found to have a malignancy. A total of 45 of 90 patients (50 percent) had developed malignancies. This is an extremely high mortality from cancer, when one considers that the overall population mor tality from malignancy is approximately 16 percent. An additional seven patients died from the pulmo nary-cardiovascular complications of pulmonary asbestosis. Four of the patients in the autopsy group also had a second primary malignancy. These malig nancies are not recorded in the Table as they were CHEST, VOL. 64, NO. 5, NOVEMBER, 1973 Downloaded from www.chestjournal.org by guest on August 24, 2009 Copyright 1973, by the American College of Chest Physicians 644 BOROW ET AL Table 1--Clinical Data of 90 Patientt with Pulmonary Asbettosi* * Malignancy, Location Lung Mesothelioma G.I. Other 48 Autopsies 26 Ca. 7 8 7 4 f 3 pancreas (5442%) \ 1 kidney 42 Surgical Procedures 19 Ca. 7 (45.2%) f 1 tongue I 1 bladder 2 5 5 I 1 lymphoma l 2 rhabdomyosarcoma Total 45 Ca. 14 (50%) 10 12 9 *Of 600 asbestos workers who worked at least 20 years in the industry up to 1959, 200 have died. Ninety of these patients were treated in one hospital. incidental and not the cause of death. The high incidence of gastrointestinal malignancies in pa tients with asbestosis makes one wonder if the inges tion of asbestos fiber can be detrimental. Fibers have been demonstrated in a number of tissues, including parietal pleura, gastric and intestinal mucosa, spleen and liver. It has been shown by Selikoff et aln and Doll12 that the risk of lung cancer among asbestos workers is from six to ten times the expected rate. Like mesothelioma, there is a time interval between the initial exposure to asbestos and the onset of the pulmonary malignancy. This latent period is similar to that seen with mesothelioma, averaging 20 to 30 years. However, there does seem to be a difference in the amount of exposure needed for the production of these malignancies. It is our impression that the worker who has the longer exposure to asbestos and thus the greater degree of pulmonary asbestosis, is more apt to develop bronchogenic carcinoma than the worker with lesser exposure who is more likely to develop mesothelioma. This reasoning is substanti ated by the age difference in patients developing the two malignancies. The average age of the patient with mesothelioma is 54 years, while the average age of the patient with bronchogenic carcinoma is approximately 10 years older. Unlike other series in which there have been a significant number of patients with mesothelioma who had only an environmental exposure to asbes tos, we have only two proved cases of paraoccupational exposure. The remainder of our patients had an industrial history. The failure to find patients with neighborhood exposure has been surprising to us as there had been, until the last several years, significant air pollution, with asbestos fiber over cer tain sections of a densely populated area in the vicinity of the asbestos mill. Another disturbing feature in our series is the overwhelming predominence of men who developed mesothelioma within the industry. Historically, women have been employed for almost half a cen tury in this mill and have worked in one of the dustiest areas of the plant, namely in textiles. Yet we have only one woman with mesothelioma who worked in this division. This again is in contrast to the series from England where there is a high inci dence of mesothelioma among female textile asbes tos workers. The perplexities involving mesothelioma and as bestos exposure are not solely confined to our series, but seem to occur all over the world. Investigators in other parts of our globe have examined the distribu tion and frequency of mesothelioma and have al ways found a strong relationship between the pres ence of this disease and exposure to asbestos fiber. Most of the cases have occurred in South Africa where the fiber is mined or in the United Kingdom where the fiber is processed, and in this hemisphere in the mining fields of Canada and the processing mills of the United States. There have also been cases reported in Germany where there is a signifi cant asbestos industry. In the Netherlands, 22 of 25 cases of mesothelioma were associated with employ ment in a shipyard using asbestos products for insu lation.13 Despite a thorough search, no mesothe liomas have been found associated with the anthophyllite asbestos production in Finland.14 One would therefore question whether these malignan cies are due to one or more specific varieties of asbestos fiber. There are six different varieties of asbestiform fibrous minerals, and among these there are striking differences in chemical and physical composition. All are silicates, crystalline in nature, and character istically are divisible into very small fibrils. Chryso lite, which is the most commonly used fiber in North America, and anthophyllite contain greater amounts of magnesium than either crocidolite or amosite, which contain more iron. In the United States and United Kingdom, chrysolite and crocidolite, and amosite to a lesser degree, are used in the various asbestos milling processes, so that workers are ex posed to all three, although in different proportions. There is some documentary evidence suggesting that chrysolite is less carcinogenic and causes less pulmonary fibrosis than the other fibers. Neverthe less, it has been shown clinically and experimentally that Chrysolite is a factor in the development of mesothelioma. In the asbestos mill where our patient series origi nates, chrysolite is the main fiber used, although in some of the processes crocidolite is also present. As CHEST, VOL. 64, NO. 5, NOVEMBER, 1973 Downloaded from www.chestjournal.org by guest on August 24, 2009 Copyright 1973, by the American College of Chest Physicians MESOTHELIOMA FOLLOWING EXPOSURE TO ASBESTOS 645 far as can be determined, chrysolite is the only fiber used in the textile division. It is interesting to note that all the cases of mesothelioma in our group have occurred since the asbestos mill has been using pre dominantly chrysolite. These paradoxes are repeated in other geographic areas. For example, the distribution of mesothelioma in South Africa is puzzling. In the mining and mill ing of crocidolite in the Northwest Cape, there has been unusually high incidence of mesothelioma from both occupational and environmental expo sure. Two hundred miles away, in the Transvaal region where the same kind of fiber is mined, there have been no reported cases of mesothelioma. Both mines have been in operation for the same period, using similar mining procedures and techniques. Sluis-Cremer15 has studied the geographic and environmental differences in these two areas and has not been able to explain the absence of mesothe lioma in the Transvaal region. Other than the mineralogic differences between the two areas (there is some amosite present in the Transvaal area), he found no variation in the intensity or length of production of these fields or in the extent of en vironmental pollution and incidence of pulmonary asbestosis. It would seem that these discrepancies, both from our own study as well as others throughout the world, indicate that there is some element in addi tion to asbestos which is essential in the develop ment of mesothelioma. It seems likely that there are other factors which act as cocarcinogens with as bestos to produce these malignancies. Selikoff8,10'11 has pointed out that cigarette smoking is a cofactor together with asbestos for the production of bron chogenic cancer. Only 3 of our 70 patients with mesothelioma did not smoke. In a recent report from the Mayo Clinic, Oels et al16 reported 37 patients with diffuse pleural meso thelioma, only 10 of whom had a definite or proba ble history of exposure to asbestos and in only 11 of whom asbestos bodies were found. Experimentally, it has been demonstrated that a few foreign materi als other than asbestos, such as diatomaceous earth17 and polyurethane,18 when instilled in the pleural cavity of animals, can induce mesothelioma. Despite these few isolated cases, the association of asbestos with mesothelioma is so overwhelmingly strong that one must consider the asbestos fiber with one or more cofactors as direct causal agents in the development of mesothelioma. Attention has been directed to the incidence of asbestos bodies found in the lungs of nonindustrial workers living in major urban areas. Reports from Pittsburgh,19 Montreal,20 New York,21 Miami,22 Israel,23 and Belfast24 have revealed that with di rect examination of lung tissue or juices pressed from such tissues, there is a greater than 25 percent incidence of asbestos bodies in the general public. Wright25 and others argue that not all of these bodies represent coated asbestos fibers. It seems reasonable to assume that if they are found in a person who has a history of exposure or possible exposure to asbestos fiber, they are indeed asbestos bodies. The quantitative estimate of a number of struc tures found in the lungs of the general public is a small fraction of the number found in the lungs of those who had been occupationally exposed. The questions which arise and have yet to be answered are: if these structures truly represent asbestos fiber, are they sufficient in quantity to produce a health hazard, and will increased use of asbestos in the manufacture of products increase public environ mental exposure? At present, there does not seem to be any health hazard for the general public. Most of the asbestos products with which they come in con tact have asbestos which is tightly bound and not liberated into the air. It is for the mill worker and industrial worker, who are exposed to asbestos prod ucts where the fiber is loosely bound and can readily escape into the air, that the health hazard exists. For the protection of this segment of our society, which numbers three to four million workers, including not only those in the asbestos industry, but those in other industries where loosely-bound asbestos prod ucts such as insulation are used, it will be necessary to establish safety measures to reduce the fiber con tent in the air, and to determine what other factor or factors act with the asbestos to produce these malig nancies. References 1 Wagner JC, Sleggs CA, Marchand P: Diffuse pleural mesothelioma and asbestosis exposure in North Western Cape Province. Br J Ind Med 17:260-271, 1960 2 Wagner JC: Epidemiology of diffuse mesothelial tumors: Evidence of an association from studies in South Africa and United Kingdom. Ann NY Acad Sci 132:575-578, 1965 3 Mancuso TF, Coulter EJ: Methodology in industrial health studies. Arch Environ Health 6:210-226, 1963 4 Hourihane DO: The pathology of mesotheliomata and an analysis of their association with asbestos exposure. Thorax 19:268-278, 1964 5 Enticknap JB, Smither WPJ: Peritoneal tumors in asbes tosis. Br J Ind Med 21:20-31, 1964 6 Newhouse ML, Thompson H: Epidemiology of meso thelial tumors in the London area. Ann NY Acad Sci 132:579-588, 1965 7 Whitewell F, Rawcliffe M: Diffuse malignant pleural mesothelioma and asbestos exposure. Thorax 26:6, 1971 8 Selikoff IJ, Churg J, Hammond FC: Relations between exposure to asbestos and mesothelioma. N Engl J Med CHEST, VOL. 64, NO. 5, NOVEMBER, 1973 Downloaded from www.chestjournal.org by guest on August 24, 2009 Copyright 1973, by the American College of Chest Physicians 646 272:560-565, 1965 9 Borow M, Conston A, Livomese L, et al: Mesothelioma and its association with asbestosis. JAMA 201:587-591, 1967 10 Selikoff IJ: Personal communication 11 Selikoff IJ, Churg J, Hammond EC: Asbestos exposure and neoplasia. JAMA 188:22, 1964 12 Doll R: Mortality from lung cancer in asbestos workers. Br J Ind Med 12:81, 1955 13 Stumplies, Meyer: Asbestos bodies and mesothelioma. Ann Occup Hyg 11:283, 1968 14 Kiviluoto R, Meurman L: Results of asbestos exposure in Finland, Proceedings of International Conferences on Pneumoconiosis, Department of Mines, Republic of South Africa, 1969, to be published 15 Sluis-Cremer GK: Asbestosis in South Africa: Certain geographical and environmental considerations. Ann NY Acad Sci 132:215-234 16 Oels HC, Harrison EG, Carr DT, et al: Diffuse malignant mesothelioma of the pleura: A review of 37 cases. Chest 60:564-570, 1971 BOROW ET AL 17 Smith WE: Personal communications 18 Hueper WC: Cancer induction by polyurethane and polysilicone plastics. J Natl Cancer Inst 33:1005, 1964 19 Utidjian MD, Gross P, de Treville RTP: Ferruginous bodies in human lungs: Prevalence at random autopsies. Arch Environ Health 17:327, 1968 20 Andilvel WM: The incidences of asbestos bodies in the lungs at random necropsios in Montreal. Can Med Assoc J 95:1179, 1966 21 Berkley C, Langer AM, Boden V: Instrumental analysis of inspired fibrous pulmonary particulates. Trans NY Acad Sci 30:331, 1967 22 Thompson JG, Graves WM: asbestos as an urban air contaminant. Arch Pathol 81:458, 1966 23 Polliack A, Sacks MI: Prevalence of Asbestos bodies in basal lung smears. Isr J Med Sci 4:223, 1968 24 Elmes PC, McCaughey WTE, Wade EL: Diffuse meso thelioma of the pleura and asbestos. Br Med J 1:350, 1965 25 Wright GW: Asbestos and health in 1969. Am Rev Resp Dis 100:467-479, 1969 ANNOUNCEMENTS 15th Conference on Medical Aspects of Sports The 15th Conference on the Medical Aspects of Sports will be held in Anaheim, California, December 1, in conjunction with the convention of the Ameri can Medical Association, November 30-December 1. The theme for the conference is "Health Care for the Athlete: A Community Concern." 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CHEST, VOL. 64, NO. 5, NOVEMBER, 1973 Downloaded from www.chestjournal.org by guest on August 24, 2009 Copyright 1973, by the American College of Chest Physicians Mesothelioma following Exposure to Asbestos: A Review of 72 Cases Maxwell Borow, Alfred Conston, Lawrence Livornese and Norbert Schalet Chest 1973;64; 641-646 DOI 10.1378/chest.64.5.641 This information is current as of August 24, 2009 Updated Information & Services Open Access Permissions & Licensing Reprints Email alerting service Images in PowerPoint format Updated Information and services, including high-resolution figures, can be found at: http://www.chestjournal.org/content/64/5/641.citation Freely available online through CHEST open access option Information about reproducing this article in parts (figures, tables) or in its entirety can be found online at: http://www.chestjournal.org/site/misc/reprints.xhtml Information about ordering reprints can be found online: http://www.chestjournal.org/site/misc/reprints.xhtml Receive free email alerts when new articles cite this article. 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