Lymphatic and hematopoietic cancer in teachers.

A recent study found high rates of leukemia and related disorders among teachers. This finding may be related to exposure to childhood infections. Therefore, epidemiologic studies on the risk of lymphatic and hematopoietic cancer among teachers were systematically reviewed. Altogether 26 relevant investigations were identified, most from ad hoc publications rather than from scientific journals. Elevated risks of leukemia, lymphoma, and multiple myeloma were found in studies using proportional mortality or mortality odds ratios as outcome measures. However, these observations may reflect low overall mortality and do not necessarily indicate high death rates from the cancers of interest. In studies deriving standardized mortality or incidence ratios, the risk estimates were generally lower. The most striking finding was for non-Hodgkin's lymphoma (approximate summary relative risk 1.36, 95% confidence interval 1.13-1.62), but it was likely to have been exaggerated by publication bias. In conclusion, no compelling epidemiologic evidence exists for a hazard of leukemia or related diseases among teachers.