Menopausal hormone therapy for breast cancer patients: what is the current evidence?

Many breast cancer survivors struggle with menopausal symptoms due to oncological treatment-induced hormone deficiency, or because they experience menopause some years after completing treatment, but have limited menopause treatment options. Estrogen replacement therapy is the most effective treatment for menopausal symptoms, but is not recommended after breast cancer because it can increase the risk of relapse. Our objectives were to review the evidence and develop a consensus statement to define the role of menopausal hormone therapy after breast cancer, and to highlight evidence gaps to inform future research.

A 25-member multidisciplinary panel developed the consensus statements using a modified Delphi methodology. The panel consisted of 18 senior doctors who voted (5 GP menopause specialists, 5 gynecologists, 4 medical oncologists, 3 breast surgical oncologists, and 1 breast radiologist), and 7 members who did not vote (4 patient representatives, 1 medical oncologist, 1 urologist and 1 administrator). Consensus was defined as ≥70% agreement with low-to-moderate variation in extent of agreement (mean absolute deviation from median of ≤0.75). We reviewed current evidence relating to use of vaginal and systemic menopausal hormone therapy ("MHT", also known as "hormone therapy," "HT" or "hormone replacement therapy," "HRT") after breast cancer diagnosis, and adjuvant endocrine (anti-estrogen) therapy, and developed a narrative synthesis. Finally, four additional breast cancer specialists peer-reviewed the manuscript.

The panel agreed that some women may choose to take MHT, (off-label use) and accept an increased risk of relapse in exchange for relief from menopausal symptoms and an improved quality of life, and that preferences may vary according to individual circumstances and the absolute risk of relapse. All respondents agreed or strongly agreed with statements supporting shared decision making and individualized menopause care (MADM 0.29).In our review of the literature, we found mainly moderate quality evidence concerning use of vaginal and systemic estrogen after breast cancer, and high quality evidence concerning the benefits of anti-estrogen therapy for estrogen receptor positive breast cancer. Based on the available data, we recommend that shared decisions are based on (1) an individual's menopausal symptoms and impact on quality of life, (2) the potential increase in an individual's risk of relapse by use of menopausal hormone therapy, and (3) patient preferences, views and treatment goals. Clinicians and patients can use our findings to make informed menopause treatment choices after breast cancer. We strongly recommend registering all patients considering MHT after breast cancer in a clinical study (eg, MENopausal hormone therapy and Outcomes After Breast Cancer, the MENO-ABC trial).