A study found that 1 to 2 years after combination hormone replacement therapy (HRT) is stopped, breast cancer risk drops back to pre-HRT levels. Combination HRT has both estrogen and progesterone. These results were presented at the 2008 San Antonio Breast Cancer Symposium.
Researchers analyzed data from the large Women's Health Initiative (WHI), which has more than 15,000 participants. Earlier information from the WHI helped doctors understand the association between higher breast cancer risk and combination HRT used to manage menopausal side effects.
In this study, the researchers found that women who weren't taking combination HRT had a 65% to 95% lower breast cancer risk compared to women taking combination HRT. But 1 to 2 years after stopping HRT, women who had been taking HRT had the same breast risk as women who never took HRT.
The researchers also looked at data from another study that showed women who had taken HRT and were then diagnosed with breast cancer were more likely to survive breast cancer compared to women who never had taken HRT before diagnosis. The researchers aren't sure why HRT, which raises breast cancer risk, would make women who had taken it more likely to survive breast cancer.
Menopausal side effects can dramatically reduce some women's quality of life. These women have to weigh the benefits of HRT against the risks. If you're having severe hot flashes or other side effects from menopause and are considering taking HRT, talk to your doctor about how you can minimize your breast cancer risk. Be sure to discuss the pros and cons of different types of HRT and how you can take HRT for the shortest time possible. The research findings reviewed here suggest that once you stop taking HRT, your breast cancer risk will return to what it was before you started.
Keep these two points in mind when you talk to your doctor:
- Estrogen-only HRT appears to increase breast cancer risk less than combination HRT.
- Research shows using combination HRT for fewer than 3 years doesn't significantly raise breast cancer risk.
Together, you and your doctor can decide if HRT or another treatment might be right for you and your unique situation. If you do decide to use HRT, try to make healthy lifestyle choices that can lower your breast cancer risk. During and after HRT, make sure to follow the recommendations for breast cancer screening, including monthly breast self-exams, annual mammograms, and physical examinations by your doctor.