Abstract:
Malignant Mesothlioma (MM) is an uncommon tumor; only about 3000 cases are diagnosed annually in the United States. Epidemiological studies have consistently confirmed that the pre-eminent risk factor for the development of mesothelioma is exposure to asbestos in a variety of occupational and environmental settings. However, debate continues regarding clinical risk factors associated with the development of MM. The Beta Carotene and Retinol Efficacy Trial (CARET) of vitamin chemoprevention of cancer, has followed 4060 men who were heavily exposed to asbestos for 10 to 18 years, with 40 cases of MM occurring in this cohort. MM incidence rates for 1989-2005 were analyzed using a stratified proportional hazards model. The study confirmed excessive rates of MM among participants with radiographic parenchymal changes (RR 2.99; 95% CI 0.87, 10.3) and pleural thickening (RR2.30; 95% CI 0.70, 7.55) respectively.