Coffee consumption and the risk of breast cancer.

The relationship of breast cancer to coffee drinking habits was evaluated in a case-control study of 616 women with breast cancer and 616 control subjects with nonmalignant disorders, apparently unrelated to coffee consumption. Compared with women who had never drunk coffee, the relative risk estimates for those women who drank less than two, two or three, and four or more cups each day were 1.5, 1.3, and 1.0, respectively. There was no apparent association with duration of consumption or use of other methylxanthine-containing beverages. The results were not modified by several potential confounding factors, including the major risk factors for breast cancer. The findings suggest that coffee consumption does not increase the risk of malignant neoplasms of the breast.