Lung cancer and mesothelioma during prospective surveillance of 1249 asbestos insulation workers, 1963-1974

Subcutaneous fluid port-associated soft tissue sarcoma in a cat

A 20-year-old male castrated domestic longhair cat was evaluated for assessment of its chronic kidney disease (CKD) and a non-healing ulcerated mass at the site of a previously placed and subsequently removed GIF tube. The cat had been diagnosed with CKD 10 years prior and two GIF tubes had been placed over a 5-year period, the second of which was associated with secondary infection. Biopsy of the non-healing ulcerated mass was consistent with grade 2 soft tissue sarcoma. At necropsy there was a discrete, serpentine, subcutaneous mass measuring approximately 8 mm in diameter that extended approximately 20 cm along the dorsum to the caudal thorax, following the path of the GIF tube, from the main intrascapular, ulcerated mass where the fluid port injection site was located. This is the first report of a fibrosarcoma arising at the site of a subcutaneous fluid port in a cat. Although the cat’s owners were pleased with the 4 years of quality of life provided by this device, this complication should be considered when a decision to place ports for long-term management of disease is made.

Mesothelioma: path to multimodality treatment

Multimodality treatment of malignant pleural mesothelioma (MPM) with surgery, radiation therapy, and adjuvant or neoadjuvant chemotherapy is the sole path to extended survival for select patients with favorable prognostic factors. No single-modality approach has produced equivalent results. Much effort has been expended since first recognition of this insidious pleural cancer to elucidate the underlying cause and optimal treatment strategy. Despite recent breakthroughs, the principal barrier to achieving a cure rests with the propensity for disease recurrence in the ipsilateral hemithorax. Despite these limitations, however, the results hold promise for improved survival with further refinement in patient selection and targeted therapy. Other approaches to multimodality treatment have capitalized on an array of innovative technologies in search of the silver bullet strategy that will ultimately undermine the biological behavior demonstrated by MPM. These range from the use of different means of radiation delivery, biological agents, virally mediated gene therapy, photodynamic therapy, and immunotherapy. Additionally, studies using gene ratios will yield more accurate means by which to diagnose, distinguish prognosticators, and more selectively assign patients to aggressive treatments. In light of the current worldwide epidemic, the lessons learned over the past several decades serve as a humbling reminder of the treatment barriers that remain.

Select mortality and cancer incidence among residents in various U.S. communities that received asbestos-contaminated vermiculite ore from Libby, Montana

In response to the significantly elevated asbestosis mortality rates found in Libby, Montana, in 2000, this analysis evaluated whether other communities throughout the United States that received asbestos-contaminated vermiculite ore from Libby experienced similar excess rates of asbestos-related diseases. Standardized mortality ratios were calculated using state death certificates, and standardized incidence ratios were calculated using cancer registry records for populations living near facilities that processed or received Libby vermiculite. This analysis focused primarily on diseases that are directly associated with asbestos exposure (e.g., asbestosis; cancer of the peritoneum, retroperitoneum, and pleura, including mesothelioma; and mesothelioma). Lung cancer and cancers of the digestive system, also associated with asbestos exposure, were not included in the analysis because they have additional risk factors for which exposure information was not available. Data from 70 unique sites in 23 states were evaluated. No statistically significant excesses of asbestosis mortality similar to those in Libby were noted; however, 11 sites (plus a state with 6 pooled sites that were counted as 1 site) had excess rates of mesothelioma and cancer of the peritoneum, retroperitoneum, and pleura. Further investigation should be conducted at these sites with excess rates of mesothelioma and cancer of the peritoneum, retroperitoneum, and pleura by participating state health departments to determine whether exposure to Libby vermiculite might have been a contributing factor.

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).

In vitro killing of human malignant mesothelioma by photodynamic therapy

Photodynamic therapy was investigated as a potential new modality for the treatment of human malignant mesothelioma (HMM) utilizing the H-MESO-1 HMM cell line and the photosensitizing agent, Photofrin-II (PF-II). Up-take of PF-II by H-MESO-1 was documented by incubating H-MESO-1 cells with PF-II and measuring the fluorescence at 625 nm following excitation at 400 nm. Cytotoxicity of photodynamic therapy was determined by incubating H-MESO-1 cells (2 X 10(5)) in microtiter plates for 24 hr with concentrations of PF-II varying from 0 to 10 micrograms/ml. The wells were exposed to gold vapor laser light (628 nm) in doses ranging from 0 to 24,000 J/m2. Twenty-four hours following treatment, [3H]thymidine (1 microCi) was added to each well. Cells were harvested 24 hr later and counted for tritium incorporation. Five replicates were performed for each combination of light and drug. Peak absorption of PF-II by H-MESO-1 was reached within 8 hr. Maximal doses of light alone caused minimal cell killing. PF-II without light was cytotoxic only at the highest concentrations. However, the combination of PF-II at concentrations at or above 2.5 micrograms/ml and light produced a significant increase in cytotoxicity. These data demonstrate that photodynamic therapy can effectively kill human malignant mesothelioma cells in vitro.

Notification of workers at high risk: an emerging public health problem

During the last two decades, an increasing number of epidemiologic studies have found cohorts of workers to be at high risk of work-related chronic diseases, especially cancers. These studies frequently have led to the broad recognition of occupational hazards and eventually to the prevention of exposures to such hazards. Generally, however, the individual cohort members found to be at high risk have not been notified of study results, and programs of medical intervention or of palliative services directed at these individual workers have not been developed. Recently, the issue of whether or not workers have a right to be notified more directly about known health hazards to which they may have been exposed has emerged as a major, unresolved question in public health policy. Issues of concern include the criteria that should guide notifications; whom, when, and how to notify; and who should pay for notification and follow-up services. This commentary discusses the scientific, ethical, economic, and institutional aspects of worker notification, and describes three new demonstration projects that have provided notification and intervention for workers at high risk of bladder, colon, and lung cancer.

Malignant mesothelioma. The Eastern Cooperative Oncology Group (ECOG) experience

The Eastern Cooperative Oncology Group has conducted a retrospective review of their experience of 96 patients with a tissue diagnosis of malignant mesothelioma treated between 1972 and 1980 on four separate sarcoma chemotherapy protocols. Thirty-two of the 96 patients were diagnosed and treated in South Africa. There were 75 males and 21 females with an age range of 27 to 78 with a median of 58.1 years. All, except for 28 patients, had some form of prior therapy. The median time from the onset of symptoms to diagnosis was 12 weeks; from the diagnosis to randomization was 15.1 weeks. Only 12 of the 96 patients demonstrated an objective regression. The responses were 7/51 on Adriamycin with 2 complete responses (complete responses--38 weeks and 52 weeks), 2/24 on Adriamycin combinations, 2/7 on cycloleucine, 1/3 on bleomycin, and 0/10 on non-Adriamycin combinations. Only 1/28 responded to a cross-over therapy (Adriamycin). The median survival from the start of protocol chemotherapy was 7.4 months and 7.5 months for Adriamycin treated patients. The median survival for responders was 29.9 months, compared to 6.3 months for nonresponders. The median survival for this entire series from the time of first symptoms was 15.2 months. The median survival for the 7 patients with abdominal mesothelioma was 12 weeks. There was a slight improvement in survival for the South Africans as compared to the Americans. Malignant mesothelioma in this series, was a rapidly lethal, nonresponsive disease whose treatment will require new therapies.

Sister-chromatid exchange and cell kinetics in CHO-K1 cells, human fibroblasts and lymphoblastoid cells exposed in vitro to asbestos and glass fibre

Possible mutagenic activity of the asbestos dusts crocidolite and chrysotile, and fine and coarse glass, was assessed in CHO-K1 cells, human fibroblasts and human lymphoblastoid cells using the sister-chromatid exchange assay and by examining the effects on cell kinetics. Asbestos caused no dose-related increase in sister-chromatid exchange levels in any of the cell types. However, mitotic delay was induced in CHO-K1 cells and human fibroblasts. The order of magnitude of induced delay in CHO-K1 cells was chrysotile greater than fine glass greater than crocidolite greater than coarse glass. Mitotic inhibition was more pronounced in these cells if they were still in suspension when initially exposed to the dusts compared with 1 h after plating.

Exposure to asbestos: psychological responses of mesothelioma patients

Thirty-eight patients with a diagnosis of malignant mesothelioma participated in a semi-structured interview to evaluate asbestos exposure, acquisition of increased risk information, and retrospective reporting of cognitive and behavioral reactions (particularly smoking behavior) to risk information. Twenty-eight patients (74%) had direct occupational contact with asbestos, and six patients (16%) reported indirect nonoccupational exposure to asbestos. Only two (10%) of the directly exposed patients acquired risk information from professional sources prior to diagnosis of mesothelioma. The most frequently reported reaction to learning of increased risk of cancer was a denial of the risk by minimizing personal exposure. Few patients reported being concerned about the information of increased risk. Smoking behavior did not change as a result of risk information, nor was there any increase in visits to physicians. Guidelines for psychosocial management of at-risk groups are recommended.

High-dose methotrexate with citrovorum factor and vincristine in the treatment of malignant mesothelioma

The incidence of malignant mesothelioma has increased greatly in the last 40 years. Current and recent past exposure to asbestos is expected to substantially increase this incidence. We report nine cases of malignant mesothelioma which temporarily responded to treatment with high-dose methotrexate-citrovorum rescue and vincristine. Further clinical trials of high-dose methotrexate with citrovorum rescue appear indicated in this disease.

Mortality patterns of rock and slag mineral wool production workers: an epidemiological and environmental study

An epidemiological and environmental study of rock and slag mineral wool production workers was undertaken at a plant that has been in operation since the early 1900s. Size characteristics of fibres produced by each process at the plant and data from industrial hygiene surveys were used to evaluate current and past exposures. These data suggest that the average historical airborne fibre concentration probably did not exceed 2.5 fibres/cc before 1935 and 1.0 fibre/cc after 1935. A retrospective cohort mortality study was designed to assess mortality patterns. Detailed occupational histories were compiled on all plant employees. All jobs in the plant were assigned to one of eight potential exposure categories to assess the extent and severity of mineral wool exposure and the effect of other significant exposures on employee mortality. Findings included an increase in the number of deaths due to cancer of the digestive system and non-malignant respiratory disease among workers who had over 20 years' exposure to mineral wool or who had survived 20 years since their first exposure to mineral wool. These findings are not inconsistent with those of Enterline's (Symposium on Biological Effects of Mineral Fibres, Lyon, France, September 1979) in the Thermal Insulation Manufacturers' Association's mortality study of men employed in four mineral wool plants.

Features of asbestos-exposed and unexposed mesothelioma

Thirty-six histologically confirmed cases of pleural and peritoneal mesothelioma have been observed in a chest unit over a period of 53 months. The past asbestos exposure was assessed by a standardized questionnaire in all cases and the asbestos lung burden was determined by means of mineralogical analysis of lung-related biological specimens (sputum, bronchoalveolar lavage fluid, lung tissues) in 28 cases. The results of these two methods were found in good agreement. Past asbestos exposure has been definitely implicated in 17 cases and definitely eliminated in 10 cases. The results were inconclusive in other cases. The group with definite past asbestos exposure was different from the nonasbestos-exposed group by clinical, biological, pathological, and prognosis features that were analyzed. In cases without past asbestos exposure there were no other possible causative agents. Younger age and similar incidence in men and women suggest an environmental or natural disease.

The need to control asbestos fibers in potable water supply systems

Occupational studies have shown that asbestos is a human carcinogen. Because many inhaled asbestos fibers deposited in the lung are cleared and swallowed, workers are also exposed through ingestion. Of the millions of current and former workers who have been heavily exposed to asbestos, one in ten will die from cancer of the gastrointestinal tract. A number on the order of 1 in 1,000 ingested asbestos fibers penetrate the digestive tract and ingested fibers have been recovered in such tissues as kidney, intestine, liver, and urine. One animal study showed tumor production related to ingestion of asbestos-containing material but, in general, the results of seven animal feeding studies have been inconclusive. A statistically significant relationship between male lung and stomach cancer and female peritoneal, gall bladder, and esophageal cancer and asbestos counts in drinking water was determined in one epidemiology study. Increased rates for male stomach and lung, and female pancreatic cancer related to asbestos in drinking water were reported in another study but possible occupational exposure made it difficult to draw conclusions. Data on excess gastrointestinal cancer among occupational groups has been used to estimate that drinking water containing 300,000 asbestos fibers per liter over a lifetime will result in one additional cancer among 100,000 people.

Osteoclastoma-like giant cell tumor of the liver

A rare, osteoclastoma-like giant cell tumor developed in the macronodular cirrhotic liver of an 87-year-old man. Histogenetically, the tumor was considered to be of reticuloendothelial cell (Kupffer cell) origin. A brief review of the literature concerning the extraosseous giant cell tumors is included in this report.

Histopathological studies on experimentally induced pulmonary, pleural and peritoneal neoplasms in mice by intraperitoneal injection of chrysotile asbestos and N-methyl-N-nitrosourethane

The cocarcinogenic effects of asbestos are presented. In lung carcinomas induced in mice, the number of carcinomas and the time of detection of the first carcinoma per tumor-bearing animals were greater and faster in the group with chrysotile plus MNU than either chrysotile or MNU alone. This suggested that chrysotile asbestos had a promoting or cocarcinogenic effect on some carcinogens in the respiratory tract. In the group treated with chryotile alone, a tumor was found in the right pleural cavity at 15 months. This tumor microscopically was similar to the biphasic form of the human diffuse mesothelioma. Microvilli, basement membrane, and junctional apparatus were seen by electron microscope, but other cytoplasmic organelles of the tumor cells were relatively scanty. Two peritoneal tumors developed in gastric and intestinal serosa at 11 and 12 months. Light and electron microscopic studies suggested that the tumors were probably myosarcomas or fibrosarcoms.

Integrating occupational health and safety into the health education classroom

Given the startling number of job-related illnesses and injuries which occur every year, occupational health and safety, a hitherto neglected topic, deserves significant attention in the school health education curriculum. Youngsters need to be exposed to this field before they become indifferent or callous toward diseases and accidents in the workplace and while the opportunity still exists to weight health and safety considerations in selecting a career. In addition, when students take up regular employment, they cannot rely on industry, government, or organized labor to protect them fully from occupational illnesses and accidents; they must possess the skills and attitudes necessary to safeguard themselves. Occupational health and safety education in the schools can focus on general awareness, skill development, and job-specific information. The field can be easily and appropriately integrated with a number of current health education topics. Examples of integration are provided for eleven typical areas of a school health education curriculum.

Unexpected longevity of a patient with malignant pleural mesothelioma: report of a case

A 53-year-old male with untreated malignant pleural mesothelioma and with seven years survival time since the appearance of clinical symptoms is reported. Histopathological and immunological findings were at variance with those usually seen with mesothelioma. Both lymphocyte surface markers and lymphocyte function values were found to be within normal range; in contrast, in eleven mesothelioma patients who progressed and died, both numerical and functional defects in T and B lymphocytes were seen. There was potential for neighborhood asbestos exposure.

Benign pleural lesion and malignant mesothelioma

In a series of eighteen diffuse malignant mesotheliomas, five cases were encountered in which thoracic surgery with benign nontumorous diagnosis preceded the development of a malignant mesothelioma by several years. The morphological findings in three of these five cases are compared with the morphology of the tumor specimens and an attempt is made to recognize the earliest possible malignant features. Crowding of mesothelial cells, their variability in size and nuclear hyperchromatism are pointed out as warning signs. In relation to these findings, the histogenetic significance of predominantly fibroproliferative versus epithelial-like pleural lesions is discussed. A histogenetic classification, based on the studies of eighteen diffuse malignant mesotheliomas, two benign fibrous mesotheliomas, one pleural fibrosarcoma, and numerous pleural plaques as well as reactive mesothelial lesions, is offered. The therapeutic aspects are mentioned.