Estrogen and Breast Cancer – Seemingly Different Results

Only a month after it was reported in JAMA that treatment of postmenopausal women with estrogen alone didn’t increase breast cancer comes a contradictory report in the Archives of Internal Medicine. What’s one to believe?

In fact, there’s a simple explanation for this discrepancy. The first study used data from the Women’s Health Initiative (WHI) trial, which found no increase at 6.8 years. The new study is based on the Nurses’ Health Study (NHS) which ran for over 20 years. They also found no increase in breast cancer for the first 10 years, but after that the frequency increased, becoming highly significant after 15 years of use.

The bottom line (for now): women who take estrogen for the prevention or treatment of osteoporosis typically require long-term treatment, and they should look for other available options – e.g. the bisphosphonates like Fosamax®. For treating menopausal symptoms, there’s no need for long-term hormone therapy – as little as possible for as short a time as possible is the answer.