Upper Lobe Tumors And Asbestos Exposure

Each year over 2,000 new cases of Mesothelioma are diagnosed in the United Stated. More researches are conducted in order ro find a cure for this disease. A study called A Meta-Analysis of Colorectal Cancer and Asbestos Exposure  by David M. Horna, David H. Garabrant, and Brenda W. Gillespie – American Journal of Epidemiology Vol. 139, No. 12: 1210-1222 is trying to capture this phenomenon. Here is an excerpt:  A meta-analysis of the relation between asbestos exposure and colorectal cancer mortality was conducted, using published reports of 20 asbestos-exposed cohorts. In order to find asbestos type and estimates of dust exposure and in relation to lung cancer SMR and the proportion of all deaths due to mesothelioma, summary standardized mortality ratios (SMRs) for colorectal cancer were examined.

An elevated summary SMR was observed in cohorts exposed to amphibole asbestos (summary SMR = 1.47; 95% confidence interval (Cl) 1.09 2.00), but not in cohorts exposed to serpentine asbestos (summary SMR = 1.04; 95% Cl 0.81 1.33) or in cohorts exposed to both serpentine and amphibole asbestos (summary SMR = 1.03; 95% Cl 0.74 1.42). Cohorts having a lung cancer SMR greater than 2.00 had a summary SMR of 1.51 (95% Cl 1.29 1.76), and cohorts in which more than 1 % of all deaths were attributed to mesothelioma had a summary SMR of 1.24 (95% Cl 0.94 1.64), After stratifying the cohorts based on mortality due to all cancers excluding those known or suspected to be associated with asbestos exposure, lung cancer mortality was not clearly associated with colorectal cancer mortality, suggesting that the crude association between these factors may be due to misdiagnosis of lung cancer as other types of cancer in the reported causes of death. The findings of the study suggest that colorectal cancer is associated wuth amphibole asbestos exposure. The result is also suggest that asbestos might not linked to colorecteral cancer.

A second study is entitled Association of Cigarette Smoking and Asbestos Exposure with Location and Histology of Lung Cancer  by BURTON W. LEE, JOHN C. WAIN, KARL T. KELSEY, JOHN K. WIENCKE, and DAVID C. CHRISTIANI have a further investigation of lung cancers that arise in association with cigarette smoking favor an upper-lobe location while those associated with asbestos exposure favor a lower-lobe location. It is reported that an excess of adenocarcinomas (among cases) not exposed to cigarette smoke as well as among those exposed to asbestos. To examine better about the effects of cigarette smoking and asbestos exposure on location and histology of lung cancer, they analyzed data from a large case-control study that included 456 patients with stage I or II lung cancer. Patients with upper-lobe tumors tended to have had more exposure to tobacco as assessed by pack-years smoked (54.7 versus 46.2, p = 0.07) and less time since quitting smoking (3.0 versus 5.5 yr, p = 0.05). The result show a contrarary from prior reports. Asbestos exposure was also associated with an upper-lobe location of tumor. Among those with upper-lobe tumors, 14.6% had a history of significant asbestos exposure compared with 5.4% of those with lower-lobe tumors.

Please read the studies in entirety if you find these helpful and interesting.

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