Reserpine and breast cancer. A community-based longitudinal study of 2,000 hypertensive women.

To supplement several case-control studies questioning whether use of reserpine is associated with occurrence of breast cancer, we conducted a longitudinal study of nearly 2,000 hypertensive women residing in Rochester, Minn. Exposure to antihypertensive agents and subsequent incidence of breast cancer were ascertained. Expected numbers of cases, derived from local population data and from the Connecticut Tumor Registry, were compared with the numbers of cases observed in exposure groups of interest. No evidence was found of any association of reserpine use, thiazide use, or untreated hypertension with subsequent occurrence of breast cancer in these hypertensive women. In addition, several issues were investigated that warrant consideration in evaluating reports published to date, especially before conclusions are drawn as to the questionable contention that reserpine has caused breast cancer in women.