Asbestos seems to have high potency in the carcinogenesis of lung cancer and low potency in carcinogenesis of Mesothelioma. One interesting study is called, ‘Asbestos and cigarette smoke cause increased DNA strand breaks and necrosis in bronchiolar epithelial cells in vivo’ by Michael Jung, Wendell P. Davis, Douglas J. Taatjes, Andrew Churg and Brooke T. Mossman, – Free Radical Biology and Medicine – Volume 28, Issue 8, 15 April 2000, Pages 1295-1299. Here is an excerpt: ‘Abstract – Coexposures to asbestos and cigarette smoke cause increased risks of lung cancer in asbestos workers. Although these carcinogens cause DNA damage to epithelial cells in vitro via generation of reactive oxygen species (ROS), it is unclear whether they cause injury to bronchiolar epithelial cells (i.e., the target cells of lung cancers in vivo). We exposed rats to amosite asbestos, cigarette smoke, and the two agents in combination for 1, 2, and 14 d. Numbers of cells exhibiting DNA strand breaks in comparison to sham rats were then evaluated in lungs using the terminal deoxynucleotidyl transferase (TDT)-mediated dUTP-biotin nick end labeling (TUNEL) method and by transmission electron microscopy (TEM). Increases in TUNEL-positive, necrotic epithelial cells occurred after exposure to asbestos alone and in an additive fashion after smoke and asbestos in combination. These results indicate that DNA strand breakage and necrosis are prominent mechanisms of injury by asbestos fibers and cigarette smoke in vivo to epithelial cells of the respiratory tract, thus validating in vitro observations from a number of laboratories.’
A second study is called, ‘Incidence of cancer among anthophyllite asbestos miners in Finland.’ By L O Meurman, E Pukkala, M Hakama – Occup Environ Med 1994;51:421-425 – University of Turku, Department of Pathology, Finland. Here is an excerpt: ‘Abstract – A cohort of 736 male and 167 female workers of two anthophyllite mines in Finland was followed up through the Finnish Cancer Registry for cancer in 1953-91. Compared with the total cancer incidence of the east Finnish population, the men had a raised risk of total cancer (standardised incidence ratio (SIR) 1.7; 95% confidence interval (95% CI) 1.4-1.9), mainly attributable to an excess in lung cancer (SIR 2.8; 95% CI 2.2-3.6). The risk of lung cancer was somewhat higher among workers classified as heavily exposed (SIR 3.2; 95% CI 2.4-4.1) than among those moderately exposed (SIR 2.3; 95% CI 1.5-3.6) and the risk increased with increasing smoking and with increasing time of work with exposure. There were four cases of mesothelioma v 0.1 expected, all in men who smoked and had had a long and heavy asbestos exposure. Among women, a non-significant excess in total cancer (SIR 1.5; 95% CI 0.9-2.4) was found in the subgroup with heavy exposure to asbestos. Anthophyllite asbestos seems to have high potency in the carcinogenesis of lung cancer and low potency in carcinogenesis of mesothelioma in comparison with the other types of asbestos.’
A third study is called, ‘Asbestos and mesotheliomas’ by M. C. Godwin, and Juraj Jagatic, – Environmental Research – Volume 3, Issues 5-6, December 1970, Pages 391-416. Here is an excerpt: ‘Abstract – Seven selected cases with asbestos in the lungs and a mesothelioma in the pleura or peritoneum were studied intensively using routine methods, polarized light, incineration technique, and acid digestion. We found that asbestos bodies, fragments, particles, and dust could be found in hilar and mediastinal nodes regularly. We could find asbestos bodies in lymphatics being transported to the nodes. We found asbestos bodies in the spleen, abdominal tumor, and small bowel wall and dust and particles in abdominal nodes and peritoneum. We found a small mesothelioma arising in the pleura in a case of peritoneal mesothelioma. We found a squamous cell carcinoma in the right lung and a mesothelioma of the left pleura. We have concluded that asbestos is irritating mechanically and chemically and that it is distributed widely in the body by the lymphatics and blood resulting in malignancies of various types with the pleura and peritoneum being especially susceptible.’
We all owe a debt of gratitude to these fine researchers for their important work. If you found any of these excerpts helpful, please read the studies in their entirety.
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Monty Wrobleski is the author of this article, for more information please visit the following links
What is peritoneal mesothelioma?
Answer
Peritoneal mesothelioma is a relatively uncommon form of mesothelioma cancer that accounts for less than a quarter of all mesothelioma cases. It is called Peritoneal because it appears as a tumor in the pertioneum membrane of the abdomen. Exposure to asbestos is the only known cause of this disease and usually symptoms do not occur until 20 to 40 years afterward. Unfortunately, due to a lack of effective treatments, malignant peritoneal mesothelioma is often fatal and patients who are afflicted by it will live on average less than a year from the time of their diagnosis.
When peritoneal mesothelioma does becomes active victims will typically experience abdominal pains, a loss of appetite, nausea, and swelling of the abdomen. Obstruction of the bowels or hindered breathing due to tumor growth are also possible symptoms.
Generally peritoneal mesothelioma is first detected by X-rays or CT scans conducted after a patient has complained of abdominal symptoms. After an abnormality is detected doctors will perform an analysis of the peritoneum. This procedure is known as peritoneoscopy. If an abnormality is verified, the doctor will perform a ‘biopsy’ or in laymen terms obtain a tissue sample for examination by a pathologist. The pathologist will than look at the tissue under a telescope and determine if mesothelioma is present.
Once mesothelioma is diagnosed, there are two general types of treatments; systemic and localized. Localized treatments are an attempt to eliminate the cancer by either surgery or radiotherapy and treat only the immediate area of the cancer. Systemic treatments, on the other hand, are designed to combat the cancer through out the whole body, and may be used either in earlier stages or late stages of the disease.
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