Mesothelioma Can be Underestimated in Death Certificates

One problem that has plagued spouses of the deceased workers that were exposed to asbestos is showing that mesothelioma was the cause of death.  There is some evidence to suggest that the incidence of mesothelioma has been grossly underestimated.  One interesting study is called, "Validation of death certificates in asbestos workers" by
M. L. Newhouse, J. C. Wagner - Br J Ind Med 1969;26:302-307.  Here is an excerpt: "Abstract - Newhouse, M. L., and Wagner, J. C. (1969).Brit. J. industr. Med.,26, 302-307. Validation of death certificates in asbestos workers. The Registrar General has supplied the certified cause of death of 436 past workers in an asbestos factory. An attempt was made to follow up the 301 (69%) deaths which had occurred in hospital or had been the subject of an inquest or coroner's post-mortem examination. Necropsy reports were obtained for 158 (52%) of this group and histological material was reviewed in 84 (28%). The additional information, particularly that obtained from review of the histology, led to the revision and extension of the diagnosis suggested by the certified cause of death in a number of cases. The incidence of carcinoma of the bronchus had not been grossly underestimated, four additional tumours of this type were identified by scrutiny of the necropsy reports, and a further four by review of histological sections. The incidence of mesothelial tumours was underestimated, endothelioma or mesothelioma was the certified cause of death in four of the series, and a further 15 mesotheliomata were identified by review of histological material. Five patients with pleural mesotheliomata had been certified as dying of carcinoma of the lung or pleura. Ten deaths from peritoneal mesotheliomata had been attributed either to carcinomatosis without mention of a primary tumour or to cancer of the gastro-intestinal tract. Lung sections were submitted for review in 67 of the series; some degree of asbestosis was found in all but seven. Asbestosis graded as either moderate or severe was found in all the confirmed cases of carcinoma of the lung."

Another interesting study is called, "Longitudinal changes in lung function among asbestos-exposed workers" by DA Schwartz, CS Davis, JA Merchant, WB Bunn, JR Galvin, DS Van Fossen, CS Dayton and GW Hunninghake - Am. J. Respir. Crit. Care Med., Vol 150, No. 5, 11 1994, 1243-1249.  Here is an excerpt: "To prospectively identify the determinants of persistent or accelerated loss of lung function among workers occupationally exposed to asbestos and assess the relative contribution of cigarette smoking, asbestos- induced pleural fibrosis, and specific findings from bronchoalveolar lavage and high resolution CT scans, we examined the determinants of lung function changes in 117 subjects occupationally exposed to asbestos for at least 1 yr in a high exposure setting. A minimum of 20 yr was required between the first exposure to asbestos and entry into the study. Baseline studies included an independent assessment of dyspnea, lung volumes, diffusing capacity of carbon monoxide (DLCO), a chest radiograph, a high resolution CT (HRCT) scan, and bronchoalveolar lavage (BAL). Subjects were observed for an average of 2 yr (range, 0.5 to 4.0 yr), and lung function was measured on at least two separate occasions (mean, 4.1 separate tests).

During the period of observation, there was an average 1.5% decrease in the TLC and a 2.5% decrease in the DLCO. In this longitudinal data set, after controlling for age, height, pack-years of cigarette smoking, and follow-up time, persistently lower measures of TLC were independently related to moderate to severe dyspnea (p = 0.005), diffuse pleural thickening (p = 0.007), and higher concentrations of fibronectin in BAL fluid (p = 0.01). Interstitial lung disease either on the chest radiograph or HRCT scan was not independently associated with persistently lower measures of TLC during the period of observation. However, none of the clinical variables we examined were associated with an accelerated decline in TLC."

Another study is called, "Malignant mesothelioma induced by asbestos and zeolite in the mouse peritoneal cavity" by Yasunosuke Suzuki, Norihiko Kohyama - Environmental Research - Volume 35, Issue 1, October 1984, Pages 277-292.  Here is an excerpt: "Abstract - The carcinogenicity of asbestos (amosite and chrysotile) and zeolite (fibrous erionite, mordenite, and synthetic zeolite 4A) were studied in the peritoneum of 586 BALB/C male mice after a single intraperitoneal or intraabdominal wall injection. As controls, 182 mice treated with and without saline solution were used. Both asbestos types and fibrous erionite frequently produced malignant peritoneal tumors after long latency; tumors developed in 93 of 394 animals (23.6%) treated with asbestos or fibrous erionite 7 months or more after administration. All of the induced peritoneal tumors were intimately associated with marked peritoneal fibrosis, in which asbestos or erionite fibers were regularly detected. Histopathologically, 83 (73 fibrous, 9 biphasic, and 1 epithelial) of 93 were consistent with malignant mesotheliomas. Other tumors consisted of 6 plasmacytomas, 1 histiocytoma, 1 liposarcoma, 1 osteosarcoma, and 1 adenocarcinoma of the pancreas. Two of the cases of mesotheliomas were associated with plasmacytoma. In many instances, the primary site of the mesotheliomas seemed to be multiple, the favorite sites being the omentum, mesentery, serosae of the gastrointestinal and genital organs, the diaphragm, the capsule of the liver and spleen, and the abdominal wall peritoneum.

In these cases, asbestos or erionite-tissue burden followed by fibrosis was frequently observed. In addition to the 93 peritoneal tumors, 3 extraperitoneal tumors (1 fibrosarcoma and 2 rhabdomyosarcomas) were induced by amosite which was probably accidentally injected into the extraperitoneal connective issue and the striated muscle tissue of the abdominal wall, respectively. These three tumors were also intimately associated with focal fibrosis in which amosite fibers were detected. Among the three different types of zeolite, only fibrous erionite showed striking carcinogenicity and marked fibrogenicity. The erionite-induced mesotheliomas were similar to those induced by asbestos in exhibiting long latency, in gross appearance, in histology, and in close association with fibrosis. Long-term persistence of asbestos or fibrous erionite around progenitor cells of the induced tumors and the consequent fibrosis seemed to be an important precondition of the malignant transformation of the progenitor cells."

If you found any of these excerpts, please read them in their entirety.  We all owe a debt of gratitude to these researchers.