April 10, 1991

Estrogen Replacement Therapy and Risk of Breast Cancer

Author Affiliations

Vanderbilt University School of Medicine Nashville, Tenn

Vanderbilt University School of Medicine Nashville, Tenn

JAMA. 1991;265(14):1824. doi:10.1001/jama.1991.03460140052012

To the Editor. —  Colditz et al1 have made a significant contribution to our knowledge of the relationship between estrogen replacement therapy and breast cancer. I do not, however, share the authors' confidence that their results were unaffected by bias due to increased surveillance of estrogen users. Among never users, the crude incidence of breast cancer was 354 cases in 186 466 women, or 190 per 100 000 women per year (see Table 2 of Colditz et al). If current users had also had this incidence, the authors would have observed 144 breast cancers during 75 643 person-years of follow-up in the current user group. In fact, they observed 180 cases, 36 more than expected. It is plausible that these 36 excess cancers might be due to increased surveillance for breast cancer. In late 1974, publicity surrounded the diagnosis of breast cancer in the wives of the president and