A cancer registry-based study of occupational risk for lymphoma, multiple myeloma and leukaemia.

Mortality and incidence studies have suggested that agricultural workers may be at increased risk for some cancers. Case-control methods were used to investigate the relationship between farming, other occupations, and lymphoma, multiple myeloma, and leukaemia. A total of 475 male cases, aged 20 years or more, and 1425 age-matched controls were identified through the Missouri Cancer Registry for the years 1984-1985. People with smoking-related cancers were excluded as controls to minimize bias associated with farmers' reported smoking patterns. Farmers had slightly elevated risks for non-Hodgkin's lymphoma (odds ratio (OR) = 1.11) and Hodgkin's disease (OR = 1.30). The risk for leukaemia (all types) was not elevated (OR = 0.91); however, for acute lymphatic leukaemia an OR of 2.84 was detected. An OR of 2.78 (95% confidence interval = 1.09-7.07) for reticulosarcoma was observed among farmers 65 years and older. Several other occupational associations were noted which have been reported previously. Carpenters (OR = 3.10) and machinists (OR = 4.85) were at increased risk for Hodgkin's disease. An elevated risk of leukaemia was observed for mechanics (OR = 4.79). Since most previous studies of the associations between lymphatic and haematopoietic cancers and agriculture have been based on mortality data, additional studies of incident cases are suggested.