Menopausal hormone therapy use and long-term all-cause and cause-specific mortality in the Long Island Breast Cancer Study Project
Menée aux Etats-Unis à partir de données portant sur 1 508 patientes atteintes d’un cancer primitif du sein diagnostiqué en 1996-1997 et sur 1 556 témoins, cette étude analyse l’association entre l’utilisation d’un traitement hormonal substitutif de la ménopause, la mortalité spécifique et toutes causes confondues (durée médiane de suivi : 17,6 mois ; 597 décès par cancer du sein)
Previous studies have observed a reduced mortality risk associated with menopausal hormone therapy (MHT) use among breast cancer survivors. We sought to clarify whether such association could be explained by tumor heterogeneity, specific causes of death, confounding from co-morbidities or health behaviors, and a comparison group of women without breast cancer. We interviewed 1508 women newly diagnosed with first primary breast cancer in 1996-1997 (~3-months after diagnosis), and 1556 age-matched women without breast cancer, about MHT use history. The National Death Index was used to ascertain vital status after a median of 17.6-years of follow-up (N = 597 deaths for breast cancer subjects). Multivariable-adjusted Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (95%CIs) for all-cause mortality, and cause-specific HR (cHRs) for breast cancer and cardiovascular disease (CVD). The Fine-Gray model was used to account for competing causes of death. Among women with breast cancer, ever vs never MHT use was inversely associated with all-cause (HR = 0.77, 95%CI = 0.62-0.95), breast cancer-specific (cHR = 0.69, 95%CI = 0.48-0.98), and CVD-specific mortality (cHR = 0.57, 95%CI = 0.38-0.85). Difference of the association was observed in breast cancer-specific mortality according to hormone receptor (HR) status (negative tumors: cHR = 0.44, 95%CI = 0.19-1.01; positive tumors: cHR = 0.96, 95%CI = 0.60-1.53). Among the comparison group, we observed similar, but more modest inverse associations for all-cause and CVD-specific mortality. MHT use was inversely associated with mortality after breast cancer, even after accounting for competing causes of death and multiple confounders, and was evident among women without breast cancer. Potential heterogeneity by HR status requires more study.