Asbestos burden predicts survival in pleural mesothelioma

BACKGROUND: Malignant pleural mesothelioma (MPM) is a rapidly fatal asbestos-associated malignancy with a median survival time of <1 year following diagnosis. Treatment strategy is determined in part using known prognostic factors. OBJECTIVE: The aim of this study was to examine the relationship between asbestos exposure and survival outcome in MPM in an effort to advance the understanding of the contribution of asbestos exposure to MPM prognosis. METHODS: We studied incident cases of MPM patients enrolled through the International Mesothelioma Program at Brigham and Women's Hospital in Boston, Massachusetts, using survival follow-up, self-reported asbestos exposure (n=128), and a subset of cases (n=80) with quantitative asbestos fiber burden measures. RESULTS: Consistent with the established literature, we found independent, significant associations between male sex and reduced survival (p<0.04), as well as between nonepithelioid tumor histology and reduced survival (p<0.02). Although self-reported exposure to asbestos was not predictive of survival among our cases, stratifying quantitative asbestos fiber burden [number of asbestos bodies per gram of lung (wet weight)] into groups of low (0-99 asbestos bodies), moderate (100-1,099), and high fiber burden (>1,099), suggested a survival duration association among these groups (p=0.06). After adjusting for covariates in a Cox model, we found that patients with a low asbestos burden had a 3-fold elevated risk of death compared to patients with a moderate fiber burden [95% confidence interval (CI), 0.95-9.5; p=0.06], and patients with a high asbestos burden had a 4.8-fold elevated risk of death (95% CI, 1.5-15.0; p<0.01) versus those with moderate exposure. CONCLUSION: Our data suggest that patient survival is associated with asbestos fiber burden in MPM and is perhaps modified by susceptibility.     

Asbestos fiber analysis in 27 malignant mesothelioma cases.

The asbestos body counts per 5 gm wet lung tissue in 27 (23 pleural and 4 peritoneal) malignant mesothelioma cases derived from 19 autopsy and 8 surgical cases were, according to our own criteria, low level exposure in 13 cases (48.2%), moderate level exposure in 2 cases (7.4%), and high level exposure in 12 cases (44.4%). In our previous study on 235 consecutive autopsy cases, the low level exposure was considered to be environmental, the moderate level was secondary or blue collar, and the high level was occupational. In the present study, about half of the cases examined (44.4%, high level exposure) are closely related to some occupational asbestos exposure and the other half (48.2%) to environmental exposure. The type and size of asbestos fibers from the 12 cases of high level exposure were analyzed and the characteristics were compared with those of cases of low level exposure without lung cancer or mesothelioma. Most fibers analyzed (98%) were longer than 5 microns and thicker than 0.10 micron by our counting rules. In the control group, predominant fibers were tremolite or actinolite. In all the 11 pleural mesothelioma cases, the content of amosite fibers was significantly higher than in the controls. In one case of peritoneal mesothelioma, incipient asbestosis was found and the predominant fibers were crocidolite. It is suggested that the presence of amosite and crocidolite is linked to mesothelioma. The mean lengths of amosite and crocidolite, as detected by our resolution capabilities, were 36.0 and 20.9 microns, and the mean diameters were 0.51 and 0.27 micron, respectively. Both amosite and crocidolite fibers had high aspect ratios (94.2 and 115.4).     

恶性间皮瘤p16蛋白表达的研究

目的研究恶性间皮瘤与ｐ１６蛋白表达的关系。方法利用微波煮沸脱交联ＳＰ法，对３４例恶性间皮瘤病理标本进行了ｐ１６蛋白表达的研究。结果ｐ１６蛋白阳性表达率５３％（１８／３４），４７％（１６／３４）的病例细胞内缺乏ｐ１６蛋白的表达。多数存在ｐ１６蛋白表达的病例没有发现ｐ５３基因的点突变；反之，存在ｐ５３基因的点突变的病例多数都没有ｐ１６蛋白的表达。ｐ１６蛋白表达与ｐ５３基因点突变之间呈明显的负相关关系。结论恶性间皮瘤可能同时存在ｐ５３和ｐ１６基因的异常，肿瘤组织细胞内缺乏ｐ１６蛋白的表达可能与ｐ１６基因的纯合缺失有关。     

Asbestos and mesothelioma in Scotland

Summary A retrospective study of the incidence of mesothelioma in Scotland and its association with asbestos is described. For the years 1950–1967, 80 cases were traced from pathological reports and biopsy material of malignant tumours invading the peritoneum and pleura. Detailed histories of residence, occupation and degree of exposure to asbestos were obtained from relatives or friends for these 80 cases and also for two sets of controls matched for age and sex. The incidence of mesothelioma in Scotland was confirmed to be associated with exposure to asbestos and its incidence was shown to be similar to that in other areas of Britain.     

Asbestos exposure in malignant mesothelioma of the pleura: a survey of 557 cases

A series of 557 malignant mesotheliomas of the pleura diagnosed in the Trieste-Monfalcone area, Italy, in the period 1968-2000 were reviewed. The series included 492 men and 65 women, aged between 32 and 93 years (median age 69 years). Necropsy findings were available in 456 cases (82%). Occupational histories were obtained from the patients themselves or from their relatives by personal or telephone interviews. Routine lung sections were examined for asbestos bodies in 442 cases. In 109 cases isolation and counting of asbestos bodies were performed. A majority of people had histories of working in the shipyards. Asbestos bodies were observed in lung sections in 67% of the cases. Lung asbestos body burdens after isolation ranged between 20 bodies and about 10 millions of bodies/g dried tissue. Latency periods (time intervals between first exposure to asbestos and death) ranged between 14 and 75 years (mean 48.8 years, median 51.0). Latency periods among insulators and dock workers were shorter than among the other categories. High asbestos consumption occurred in many countries in the 1960s and in the 1970s. The data on latency periods obtained in the present study suggest that a world mesothelioma epidemic has to be expected in the coming decades.     

Asbestos and man-made vitreous fibers as risk factors for diffuse malignant mesothelioma: results from a German hospital-based case-control study

BACKGROUND: This study examines the role of occupational factors in the development of diffuse malignant mesothelioma with special emphasis on the dose-response relationship for asbestos and on the exposure to man-made vitreous fibers (MMVFs). METHODS: One hundred and twenty-five male cases, diagnosed by a panel of pathologists, were personally interviewed concerning their occupational and smoking history. The same number of population controls (matched for sex, age and region of residence) underwent similar interviews by trained interviewers. Odds ratios (OR) were calculated for an expert-based exposure index using conditional logistic regression. RESULTS: Exposure to asbestos shows the expected sharp gradient with an OR of about 45 for a cumulative exposure > 1.5 fiber years (arithmetic mean 16 fiber years). A significant OR was calculated even for the lowest exposure category "> 0 - < or = 0.15 fiber years". Although the mean cumulative exposure to MMVF is roughly 10% of the exposure to asbestos, an increased OR is observed in an ever/never evaluation. This observation is heavily hampered by methodical problems. A corresponding case-control study was performed using a lung tissue fiber analysis in addition to interviews. Both interviews and the lung tissue analysis yielded similar OR levels between the reference and the maximum exposure intervals. CONCLUSIONS: Despite a possible influence as a result of selection and information bias, our results confirm the previously reported observation of a distinct dose-response relationship even at levels of cumulative exposure below 1 fiber year. Moreover, the study confirms that asbestos is a relevant confounder for MMVF. A causal relationship between exposure to MMVF and mesothelioma could neither be detected nor excluded, as in other studies.     

Asbestos and peritoneal mesothelioma among college-educated men

The proportion of peritoneal mesotheliomas among all mesotheliomas has been decreasing, leading some to suggest that peritoneal mesothelioma occurs only after high levels of exposure to asbestos. To investigate the relationship between asbestos exposure and the development of peritoneal mesothelioma, a case-control study examined 40 cases of primary peritoneal mesothelioma from a single institution. This series differed from previous reports in that 75% of the cases and controls had attended college. Results show an odds ratio of 6.6 for asbestos exposure among this group of primary peritoneal mesothelioma cases with relatively slight asbestos exposures.     

Asbestos exposure and ovarian fiber burden

Epidemiologic studies suggest increased risk of epithelial ovarian cancer in female asbestos workers and increased risk of malignancy in general in household contacts of asbestos workers. Ovaries were studied from 13 women with household contact with men with documented asbestos exposure and from 17 women undergoing incidental oophorectomy. Ovarian tissue was examined by analytic electron microscopy. Significant asbestos fiber burdens were detected in 9 out of 13 women with household asbestos exposure (69.2%), and in 6 out of 17 women who gave no exposure history (35%). Three exposed women had asbestos counts over 1 million fibers per gram wet weight (23%), but only 1/17 women without an exposure history had a count that high (6%). Although asbestos has been documented as a contaminant of some older cosmetic talc preparations, the chrysotile and crocidolite types of asbestos we detected are more indicative of background and/or occupational exposure. This study demonstrates that asbestos can reach the ovary. Although the number of subjects is small, asbestos appears to be present in ovarian tissue more frequently and in higher amounts in women with a documentable exposure history. © 1996 Wiley-Liss, Inc.     

Pathology of human malignant mesothelioma--preliminary analysis of 1,517 mesothelioma cases

The author reviewed 1,517 human malignant mesothelioma cases from 1975 through August 2000. These mesothelioma cases were definite or probable in diagnostic certainty. Sources of these cases varied including asbestos insulation workers, UNARCO workers, Cancer and Leukemia B mesothelioma panel cases and random cases. Pathology materials consisted of autopsy, biopsy and rare cytology specimens. 92.3% of these patients were male, and 85.8% were between 50 and 79 years in age. The major primary site of the tumor was the pleura (73.1%). However, in a group of the asbestos insulation workers, the peritoneum was the more common primary site of malignant mesothelioma, compared to the pleura. Histologically, epithelial cell type was the majority (61.1%), followed by biphasic (22.1%) and fibrosarcomatous (16.4%). A double primary tumor (malignant mesothelioma associated with other cancer) was present in 32 of the 1,517 cases. These 32 cancers included lung cancers, renal cell carcinomas, colorectal cancers, pancreatic cancers and a cancer of the larynx, which are known to be at higher risk among asbestos insulation workers. The latency period of the vast majority (98.1%) of these mesothelioma cases were longer than 20 years. It is well accepted that cigarette smoking does not contribute to the induction of malignant mesothelioma. Indeed, the present study confirmed that 19.9% of these mesothelioma patients had never smoked cigarettes.     

Exploratory study on the detection of markers for diagnosing early-stage malignant mesothelioma

Malignant mesothelioma (MM) is a highly aggressive, incurable neoplasm associated with asbestos exposure. Early detection of MM is not easy and radiological surveillance is imperfect. The use of blood-based biomarkers might solve this difficulty and allow detection of MM at an early stage when combined treatment involving surgery, chemotherapy and radiotherapy might be effective. In the research project entitled "Comprehensive approach on asbestos-related diseases" supported by the "Special Coordination Funds for Promoting Science and Technology (H18-1-3-3-1)", we conducted an exploratory study on the detection of markers for diagnosing early-stage MM. In this study, we have shown that serum soluble mesothelin-related peptide (SMRP) is a highly specific and moderately sensitive biomarker for diagnosing MM. SMRP levels in pleural effusion were elevated not only in advanced-stage malignant pleural mesothelioma (MPM), but also in early-stage disease. SMRP in pleural effusion can be an MPM-specific biomarker with greater sensitivity than in serum, especially for the early stage of the disease. Circulating tumor cells (CTCs) and circulating endothelial cells (CECs) were considered to be useful surrogate markers of disease progression in MPM, although the lack of sensitivity for early-stage disease remains to be improved. Cytological analysis with gene expression profiling has been more effective in detecting early-stage MPM with pleural effusion. In conclusion, blood or effusion-based biomarkers, possibly in combination with other new modalities, such as a thoracoscopy combined with the advanced imaging systems consisting of autofluorescence imaging (AFI) and narrow band imaging (NBI), will show some promise for curing MPM if the disease is detected at an early stage.     

Molecular biology of malignant mesothelioma

Human malignancies develop via a multi-step that involves the accumulation of several key gene alterations with associated genetic and epigenetic events. Although malignant mesothelioma (MM) has been demonstrated to be clearly correlated with asbestos exposure, it remains poorly understood how asbestos fibers confer key gene alterations and induce cellular transformation in normal mesothelial cells, which results in the acquisition of malignant phenotypes, including deregulated cell proliferation and invasion. Malignant mesothelioma presents with the frequent inactivation of tumor suppressor genes of p16 ^INK4a /p14 ^ARF on chromosome 9p21 and neurofibromatosis type 2 (NF2) on chromosome 22q12, with the latter being responsible for the NF2 familial cancer syndrome. In contrast, MM shows infrequent mutation of the p53 gene, which is one of the most frequently mutated tumor suppressor genes in human malignancies. Genetic abnormalities of oncogenes have also been studied in MM, but no frequent mutations have been identified, including the epidermal growth factor receptor (EGFR) and K-RAS genes. Recent studies have suggested the activation of other receptor tyrosine kinases, including Met, and the deregulations of mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3-kinase (PI3K)-AKT signaling cascades, although the alterations responsible for their activation are still not clear. Thus, further genome-wide studies of genetic and epigenetic alterations as well as detailed analyses of deregulated signaling cascades in MM are necessary to determine the molecular mechanisms of MM, which would also provide some clues for establishing a new molecular target therapy for MM. This article is based upon the Symposium Lecture Series, “To Know Malignant Mesothelioma,” at the 77th Annual Meeting of the Japanese Society for Hygiene held in Osaka, Japan on March 25–28, 2007.     

Primary malignant pericardial mesothelioma]

The case-history of a 41-year-old man is reported. He was admitted because of the sudden development of left hemiparesis, loss of consciousness and increasingly deeper coma. The ECG demonstrated second-degree AV block with Wenkebach conduction or episodes with complete AV block. The colour Doppler ultrasound and cranial CT examination revealed occlusion of the right internal carotid artery and a cerebral infarct of the right hemisphere. Within 24 hours patient died from herniation of the brainstem. Postmortem examination revealed a pericardial neoplasm infiltrating both left and right atrium, AV junctional area, interventricular septum and right ventricle. The tumor tissue grew transmurally and protruded into the cavities of the heart. The right internal carotid artery was occluded by a tumor embolism. The histochemical and immunohistochemical results proved that the tumor was a primary malignant pericardial mesothelioma. This kind of cardiac tumor involving the AV node and mimicking stroke is very rare.     

Medico-legal aspects of malignant mesothelioma

The object of this investigation was to discuss medico-legal aspects of malignant mesothelioma in relation to social insurance legislation for occupational injuries and diseases in Norway. During the period 1960-79 the Cancer Registry of Norway recorded a total of 155 men and 35 women with malignant mesothelioma. However, only 21 men and no women were notified to the National Insurance Institution as occupational disease cases before 31 December 1979, in spite of the well established causal association between occupational asbestos exposure and the disease. The investigation is based on these 21 patients. The long latency period from first asbestos exposure until appearance of the disease and the short survival were evident in this study. Furthermore, the legislation and provisions for occupational injuries and diseases in Norway are obviously intended for occupational accidents, and consequently the legal assessment of patients with malignant mesothelioma was complicated. For those notified, the delay in notification was considerable, and only 50% were notified before death. Delay in the claim procedure was also substantial, and few patients survived the claim procedure period. The decisions were not consistent, particularly decisions regarding "the year of injury" and appeared to have been more restrictive during recent years. One of the 21 cases was not accepted as occupational disease, because domestic exposure was considered more probable than occupational exposure.