Identifying menopause in breast cancer patients: considerations and implications

The pivotal role for oestrogen in the aetiology and progression of the majority of breast cancers is well established; consequently, endocrine therapy is an important approach in the treatment of this disease for many women. While tamoxifen has been the mainstay of endocrine therapy for breast cancer for over 30 years, we now have a range of therapeutic manipulations, in particular utilising the aromatase inhibitors (AIs) in post-menopausal women. To date each strategy employing an AI, including primary adjuvant monotherapy, switching from tamoxifen after 2–3 years, and extending adjuvant therapy with an AI after 5 years of tamoxifen, has shown superiority compared with tamoxifen alone; however, AI monotherapy is not suitable for pre- or peri-menopausal women, and therefore, an accurate assessment of the menopausal status of each individual patient is essential. Unfortunately, defining post-menopausal status can be fraught with difficulty, especially when cancer therapy is either recently completed (e.g. chemotherapy), or ongoing (e.g. tamoxifen and/or luteinising hormone-releasing hormone analogues). This paper shall review the definition of menopause in breast cancer patients and explore the issues and implications surrounding such a definition with respect to therapy choice for patient and physician alike.