Questions Remain About Hormone Therapy and Risk for Breast Cancer Recurrence

In 1997, Swedish researchers initiated two open-label, randomized clinical trials (Hormonal Replacement Therapy After Breast Cancer — Is It Safe? [HABITS; 447 participants] and the Stockholm trial [378 participants]) to assess the safety of hormone therapy in women treated for early breast cancer. Although both studies were methodologically similar, HT in the Stockholm trial minimized progestational therapy in participants with uteri. In a 2003 interim HABITS analysis (median follow-up, 2 years), risk for breast cancer recurrence was significantly elevated in women using HT (hazard ratio, 3.5), and the trial was stopped. In the Stockholm trial, however, recurrence risk was not elevated at a median follow-up of 4 years (HR, 0.82; Journal Wat…