Case-control study of non-Hodgkin's lymphoma among women and heterosexual men in the San Francisco Bay Area, California.

A population-based case-control study was conducted between 1988 and 1995 in the San Francisco Bay Area of California to determine risk factors for non-Hodgkin's lymphoma. Participants completed in-person interviews, and blood was drawn to test for viruses and lymphocyte subsets. This report includes data for 1,281 cases and 2,095 controls. In multivariate analyses, the factors associated with a decreased risk for non-Hodgkin's lymphoma were allergy to plants, bee and wasp stings, five or more vaccinations, drugs to lower blood cholesterol, nonsteroidal anti-inflammatory drugs, total number of sexual partners, and lifetime Cannabis use, whereas an increased risk was associated with cimetidine and other histamine H2-receptor antagonists, splenectomy, gonorrhea, and body mass index. Unique to sex-specific models was an increased risk for endocrine gland disorders among women and for polio among men. Median CD3, CD4, CD8, CD20, and lymphocyte counts for non-Hodgkin's lymphoma patients were significantly lower than those for controls. These results implicate environmental factors that may influence the early stages of lymphomagenesis by stimulating the immune system. Antigen-driven B cells that accumulate to form lymphoma may be suppressed by immunologic stresses such as exposure to an increased number of sexual partners and to certain medications. A history of allergies provides evidence for a persistent capacity for B-cell differentiation and therefore a decreased accumulation of B cells. The decreased risk for non-Hodgkin's lymphoma with use of nonsteroidal anti-inflammatory drugs and cholesterol-lowering drugs is consistent with a macrophage inflammatory role in B-cell proliferation.