Objective: The aim of this study was to analyze the determinants of breast discomfort among postmenopausal women initiating menopausal hormone therapy (HT).
Methods: We analyzed questionnaire, anthropometric, and serum estrone data from the Postmenopausal Estrogen/Progestin Interventions (PEPI) Trial, a randomized trial comparing placebo, conjugated equine estrogens (CEE) alone, or CEE with a progestogen (continuous or cyclical medroxyprogesterone acetate or cyclical micronized progesterone) among postmenopausal women. HT users could join the PEPI Trial after stopping HT for 2 months. We modeled the relation between smoking, body weight, alcohol consumption, age, quitting HT for the PEPI Trial, physical activity, and α-tocopherol consumption and new-onset breast discomfort at the 12-month follow-up among 662 participants without baseline breast discomfort.
Results: The associations of new-onset breast discomfort with weight and with strenuous exercise varied by treatment assignment. Among women assigned to CEE + progestogen, strenuous exercise was associated with a 49% lower odds of new-onset breast discomfort (odds ratio, 0.51; 95% CI, 0.29-0.89; P = 0.02), whereas among women assigned to placebo or CEE alone, strenuous exercise was not significantly associated with new-onset breast discomfort. Surprisingly, among women taking CEE alone, each kilogram higher weight was associated with a 6% lower odds of new-onset breast discomfort (P = 0.04), whereas among women taking placebo, the association was in the opposite direction (P = 0.04). Adjustment for estrone level had negligible effects on odds ratios. α-Tocopherol intake, age, smoking, and alcohol intake were not significantly associated with new-onset breast discomfort in adjusted analyses.
Conclusions: Strenuous exercise and higher body weight may decrease the odds of new-onset breast discomfort among postmenopausal women initiating HT.