Breast Cancer Risk Not Increased By Estrogen Therapy
Posted Oct 22 2010 7:31am
The use of hormone therapy for the relief of menopausal symptoms has been common practice for decades. However, the safety of hormone therapy, particularly estrogen + progesterone (E+P), has been hotly debated since the publication of the Women's Health Initiative study. This major set of clinical trials reported that E+P hormone therapy increased breast cancer risk by 24% and nearly doubled the risk for death specifically due to breast cancer . In contrast, estrogen-alone therapy (ET) was shown to decrease breast cancer risk by about 23% compared to the placebo group after an average of about 7 years of follow up. In the intervening years since the publication of these data, the reasons for these results have been debated and investigated with many believing that differences in risk might be dependent on age and years after menopause when hormone therapy was started.
The results of these debates and investigations have resulted in the publication of a Position Statement from the North American Menopause Society ( free to download ). While this Position Statement covers a lot more information than just breast cancer and is worth reading in its entirety, some of the pertinent breast cancer information is described below.
Estrogen + Progesterone Therapy - Incidence of breast cancer increases after use of E+P hormone therapy past 3 to 5 years. This increase amounts to 8 additional breast cancers per 10,000 women. E+P hormone therapy increases breast cell growth, breast pain, and mammographic density. It is thought that the increased breast cancer risk with E+P hormone therapy might be due to the promotion of growth of pre-existing tumors too small to detect by examination. The increase in breast cancer risk was observed in women who started E+P therapy shortly after menopause, whereas women who waited more than 5 years after reaching menopause to start E+P therapy did not see an increase in breast cancer risk.
Estrogen Alone Therapy - Women taking ET showed no increase in breast cancer risk over an average 7 years of usage. In fact, ET was associated with 6 fewer cases of breast cancer per 10,000 women, suggesting a modest decrease in breast cancer risk. The decrease in breast cancer risk was observed in all three age groups (50-59, 60-69, and 70-79 years). When looking at breast cancer subtypes, there was a 31% reduction in risk for localized breast cancer and a 29% reduction for ductal breast cancers.
These are very important pieces of information with very different outcomes. While E+P hormone therapy appears to increase breast cancer risk, specifically in women who start E+P shortly after menopause, estrogen alone therapy appears to modestly decrease breast cancer risk. The use of E+P hormone therapy or ET in breast cancer survivors is still controversial and is being investigated.
Overall, this is good news for some women looking to relieve menopausal symptoms, while proactively trying to reduce their breast cancer risk. For these women, ET might be a viable alternative. For women looking for a more natural approach to relieving menopausal discomforts, this also suggests that natural estrogen-like substances, like many plant phytochemicals, might also be a viable alternative. While these plant substances are not the same as estrogen, they have some structural similarities and can act like estrogen in some cases, thus making them a potentially effective approach for relieving menopausal discomforts.