Hormone replacement therapy (HRT) is known to increase the risk of breast cancer in healthy women, however a new report suggests that HRT also effects the risk of breast cancer recurrence. 

A study in the Journal of the National Cancer Institute analysed follow-up data for 442 women who were previously treated for breast cancer who were enrolled in the Hormonal Replacement After Breast Cancer Is it Safe (HABITS) randomised trial. The HABITS study compared HRT for menopausal symptoms with best management without hormones among women with previously treated breast cancer. It was stopped early due to suspicions of an increased risk of new breast cancer events following HRT. Lead author Dr. Lars Holmberg, from King's College London and colleagues analysed results after an extended follow-up.

They found that during a median follow-up of 4 years, 39 of 221 HRT-treated women had a breast cancer recurrence compared with 17 of 221 women in the control group. At 5 years, the corresponding cumulative rates of recurrence were 22.2% and 8.0%. At latest follow-up, six breast cancer deaths and six surviving cases with metastatic disease were identified in the HRT group compared with five such deaths in the control group and four cases of metastatic disease. The authors conclude that "Further data from randomised studies are needed to define both the impact of specific types of HRT regimens and accompanying circumstances on the risk of recurrence in breast cancer survivors following HRT exposure" .

For further information visit The Journal of the National Cancer Institute