EDITORIAL EDITORIAL Progestins and Recurrence in Breast Cancer Survivors

Menopausal hormone therapy use in breast cancer survivors is controversial, and clinical trials of this issue have proven diffi cult. Eight years ago, two separate randomized trials of this question were begun, but accrual diffi culties led to development of a merger with a joint analysis plans. In 2004 the trials were stopped early after an interim combined analysis of the pooled data found an in-creased risk for breast cancer recurrence in the hormone group (hazard ratio [HR] = 1.8, 95 % confi dence interval [CI] = 1.03 to 3.1) relative to the control group. One study, the Hormone Re-placement Therapy After Breast Cancer — Is It Safe (HABITS), then reported substantially increased breast cancer recurrences with hormone use (HR = 3.3, 95 % CI = 1.5 to 7.4). However, risk of breast cancer recurrence in this comparison in the Stockholm trial was lower (HR = 0.8, 95 % CI = 0.4 to 1.9), with statistically signifi cant heterogeneity between the study results ( P =.02) ( 1)