Research shows that 5 or more years of combination (contains both estrogen and progesterone) hormone replacement therapy (HRT) increases breast cancer risk. Less is known about the risks of using HRT for fewer than 5 years. A study showed that women using combination HRT for 3 or more years roughly tripled their risk of 2 types of breast cancer: invasive lobular carcinoma and mixed ductal-lobular carcinoma.
These breast cancers aren't seen as often as invasive ductal carcinoma, the most common type of breast cancer. There was more invasive ductal carcinoma in women who took combination HRT for more than 3 years compared to women who did not take HRT, but the increase wasn't statistically significant, which means it could have been due to chance.
The side effects of menopause dramatically reduce quality of life for some women. They have to weigh the benefits of HRT against the risks. If you're experiencing severe menopausal side effects and are considering HRT, talk to your doctor about how you can minimize your breast cancer risk. Estrogen-only HRT may be one option.
If you do decide to take HRT, try to use it for the shortest time possible. The study reviewed here found that breast cancer risk was not significantly increased when combination HRT was used for fewer than 3 years.
Together, you and your doctor can develop a plan to manage the side effects of menopause that is right for you.