That fear comes from the 2002 Women's Health Initiative, which studied women averaging 63 years old on an older oral formulation and found a small, statistically non-significant increase in breast cancer diagnoses. Two decades of reanalysis showed the picture depends on age at start, type and route. For women who begin within 10 years of menopause, generally under 60, randomized data show lower all-cause mortality and fewer fractures. On that basis the FDA announced in November 2025, and approved in February 2026, the removal of the boxed warnings on cardiovascular disease, breast cancer and probable dementia from these products. Risks remain and are on the label: blood clots and stroke with oral estrogen (transdermal is lower), a small increase in breast cancer with long use of combined therapy, and endometrial cancer if estrogen is taken without a progestogen by a woman with a uterus. Women with a history of breast cancer, blood clots, stroke, or unexplained bleeding are generally not candidates.