Malignant lymphoma and multiple myeloma linked with agricultural occupations in a New Zealand Cancer Registry-based study.

Mortality studies have indicated that workers in agriculture and forestry may be at increased risk of developing malignant lymphoma and multiple myeloma. The authors report the findings from a case-control study of 734 male malignant lymphoma and multiple myeloma patients (International Classification of Diseases (ICD) 200-203) registered with the New Zealand Cancer Registry in the period 1977-1981 and aged 20 years or more at time of registration. Controls also were males chosen from the cancer registry with four controls per case, matched on age and year of registration. The case group contained a significant excess of the occupational category involving agriculture and forestry (odds ratio = 1.25, 95% confidence limits = 1.00, 1.56). This excess was almost entirely among those aged less than 65 years at time of registration (odds ratio = 1.45, 95% confidence limits = 1.08, 1.95), particularly among patients with multiple myeloma (ICD 203) (odds ratio = 2.22, 95% confidence limits = 1.31, 3.75) and the category including nodular lymphoma, mycosis fungoides, and unspecified non-Hodgkin's lymphoma (ICD 202) (odds ratio = 1.76, 95% confidence limits = 1.03, 3.02). Mortality from malignant lymphoma and multiple myeloma increased significantly during the period 1955-1979.