Hormonal therapy during menopause time may increase risk of breast cancer

December 30, 2015

In an accompanying editorial, Rowan T. Chlebowski, M.D., Ph.D., of Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center and Garnet Anderson from the Fred Hutchinson Cancer Research Center note the study provides substantial support for similar findings from the Women's Health Initiative (WHI) in the U.S. They add that the similarities between the patterns of breast cancer risk in these two large studies increase the likely validity of the results, especially since the methodologies of the two studies were quite different.

The editorialists also discuss discrepancies in the two studies' findings regarding the risk of estrogen-only hormone therapy; the WHI found little risk associated with estrogen alone while the MWS found a statistically significant increased risk, except in overweight and obese women. They conclude that "the question of the effect of estrogen-only formulation use on breast cancer risk in postmenopausal women, even with longer-term hormone use, still stands unanswered."

Source: Journal of the National Cancer Institute