MENOPAUSAL HORMONE THERAPY AND BREAST CANCER RISK
DOI:
https://doi.org/10.31435/ijitss.2(50).2026.5043Keywords:
Menopausal Hormone Therapy; Breast Cancer; Estrogen-Progestin Therapy; Estrogen-Only Therapy; Hormone Replacement Therapy; Recurrence Risk; Transdermal Hormones; Bioidentical Progesterone; WHI; Breast Cancer SurvivorsAbstract
Introduction. Menopausal hormone therapy (MHT) is widely used for the relief of menopausal symptoms and for the prevention of osteoporosis. However, its use remains controversial due to the potential increased risk of breast cancer, especially with combined estrogen-progestin therapy (EPT).
Aim. This review aims to critically evaluate the current evidence on the relationship between MHT and breast cancer risk, with a focus on formulation-specific effects, timing of initiation, duration of use, and risk among breast cancer survivors.
Material and methods. A structured literature review was conducted using PubMed, MED-LINE, and EMBASE databases from January 2018 to June 2025. Inclusion criteria covered randomized controlled trials, cohort and case-control studies, systematic reviews, and meta-analyses involving > 600 breast cancer cases. Studies examining systemic MHT and breast cancer incidence, subtype-specific risk, and recurrence in survivors were included. A total of 30 high-quality references were selected.
Results. Combined EPT consistently increases breast cancer risk (RR/HR~1.5-2.5), with high-er risk for long-duration use and early initiation after menopause (<3 years). Estrogen-only therapy (ET) shows a modest risk increase in observational studies, but RCT data (e.g., WHI) suggest reduced incidence and mortality. Bioidentical progesterone appears less harmful than synthetic progestins. Transdermal MHT may carry lower risk than oral formulations. Vaginal estrogen shows no significant increase in breast cancer risk. Among breast cancer survivors, systemic MHT is associated with a significantly increased risk of recurrence (HR~1.46).
Conclusions. MHT use, particularly EPT, is associated with an elevated breast cancer risk. Risk varies by formulation, duration, timing, and patient profile. Clinicians should tailor MHT decisions individually, favoring the lowest effective dose and shortest duration, while considering non-hormonal alternatives when appropriate. Systemic MHT is generally contraindicated in breast cancer survivors.
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Copyright (c) 2026 Marta Rogozińska, Natalia Bukała, Dominika Kondyjowska, Weronika Tomasiczek, Sylwia Tomasiczek, Zuzanna Sawiec, Ewa Antonowicz, Dorota Maria Komuńska
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