Study Shows Small Risk of Breast Cancer with Limited HRT

Kathleen Blanchard's picture

According to the results of a new study, a woman's risk of breast cancer is small with limited use of hormone replacement therapy (HRT). The research shows there is a safe period for combined estrogen and progesterone (E+P) hormone replacement therapy of two to three years after menopause. Breast cancer risk drops dramatically when HRT is discontinued.

The study comes from the Department of Epidemiology and Surveillance Research at the American Cancer Society, in Atlanta, Georgia; published January 20 in the journal Cancer. The authors say, "In combination, these findings suggest a window of 2 to 3 years for the risks of E+P [estrogen and progesterone] to become apparent after initial use and to attenuate following cessation."

The study results come from data extracted from the Cancer Prevention Study II Nutrition Cohort, which included 67,754 postmenopausal women.

The study still raises concerns about breast cancer and hormone replacement therapy. According to Rowan Chlebowski, MD, PhD, from the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, in California (not involved in the study) "Estrogen and progesterone increase the glandular tissue within the breast, and this makes it harder to interpret a mammogram. We can't define a safe interval for HRT." The comment is extracted from an interview with Medscape Oncology. Dr. Chlebowski authored the report on the Women's Health Initiative (WHI), published February 5 in the New England Journal of Medicine.


However, Dr. Chlebowski does say the initial risk of breast cancer for women who take hormone replacement on a limited basis is…"going to be small." HRT, taken for longer than five years does increase a woman's risk of breast cancer. Estrogen therapy alone does not have the same risks of breast cancer as combined estrogen progesterone therapy.

The authors write, "The findings from the current study suggest a window of 2 to 3 years for the risks of E + P [estrogen + progesterone) both to become apparent after initial use and to attenuate after cessation".

The results lead to recommendation than women use estrogen and progesterone hormone replacement therapy (HRT) no longer than three years after menopause, at the lowest possible dose.

Abstract: Postmenopausal hormone use and breast cancer associations differ by hormone regimen and histologic subtype.