Case-control study of diet and mesothelioma in Louisiana.

Data were analyzed from a case-control interview study of malignant mesothelioma in Louisiana, which gathered information on usual diet and on lifetime occupational exposure to asbestos. Thirty-seven patients with malignant mesothelioma of the pleura (n = 32) or peritoneum (n = 5) were matched to controls according to age, sex, race, and factors related to case ascertainment (hospital and date of diagnosis, or parish and date of death). Twenty-one of the 37 cases were judged by masked occupational review to have been exposed to asbestos (57%), compared to seven of 37 controls (19%). Seven additional cases and 10 additional controls had occupational histories suggestive of asbestos exposure. With regard to usual diet before illness, cases reported less frequent consumption of homegrown produce (p = 0.005), cruciferous vegetables (p = 0.005), and all vegetables combined (p = 0.09) than did the controls. An estimate of usual carotene intake was also significantly lower in cases (p = 0.03). Dose-dependent reductions in risk were seen with increasing consumption of vegetables, especially cruciferous vegetables (p for trend = 0.013). These associations were not explained by differences in asbestos exposure as measured by the occupational review. The results indicate that consumption of vegetables or some vegetable-related constituent may have a protective effect on developing mesothelioma.