Cancer risks among Missouri farmers

A series of case–control studies was conducted to investigate cancer risks among farmers. These studies were based on Missouri Cancer Registry data for 15,000 white male patients, including 1720 subjects classified as farmers, registered between 1984 and 1988. For each cancer site, all other cancer registrations formed the control group. The largest risks among farmers were found for lip cancer (odds ratio [OR], 3.07; 95% confidence interval [CI], 1.99 to 4.73) and cancer of the bone (OR, 2.02; 95% CI, 0.66 to 5.81). Elevated risks were observed for several other sites, including the nasal cavity and sinuses (OR, 1.66; 95% CI, 0.54 to 4.70), prostate (OR, 1.33; 95% CI, 1.18 to 1.51), non‐Hodgkin's lymphoma (OR, 1.40; 95% CI, 1.04 to 1.85), and multiple myeloma (OR, 1.40; 95% CI, 0.87 to 2.24). Other smaller elevations in risk were noticed for cancer of the rectum (OR, 1.21; 95% CI, 0.95 to 1.53), liver (OR, 1.19; 95% CI, 0.58 to 2.37), malignant melanoma (OR, 1.26; 95% CI, 0.63 to 2.45), kidney (OR, 1.21; 95% CI, 0.89 to 1.65), and leukemia (OR, 1.12; 95% CI, 0.81 to 1.55); however, some of these estimates were imprecise due to small numbers. The overall OR for lymphatic and hematopoietic cancers was 1.28 (95% CI, 1.06 to 1.56). Consistent with previous studies, a decreased risk of lung cancer was observed among farmers (OR, 0.67; 95% CI, 0.60 to 0.76). The current findings are presented in the context of other recent studies, including discussions of possible causes of farming‐associated excess cancer risk and possible sources of bias.