Endocrine consequences of breast cancer therapy and survivorship.

Breast cancer survivorship is increasing, due to earlier diagnosis of the disease and more effective therapies. Long-term endocrine sequelae, including early menopause, bone health, fertility implications and menopausal symptoms, are important survivorship issues. Ovarian failure is common with chemotherapy and options for preserving fertility in young women include ovarian suppression during chemotherapy and oocyte or embryo cryopreservation before chemotherapy. Tamoxifen as adjunct therapy in premenopausal women leads to ovarian stimulation, sometimes ovulation and occasionally pregnancy with important teratogenic implications. Aromatase inhibitor therapy with or without gonadotrophin releasing hormone (GnRH) agonist leads to profound bone loss and anti-resorptive therapy is advised to prevent fracture. Tamoxifen acts to preserve bone in postmenopausal women but not premenopausal women. Pregnancy is not discouraged in young women with early breast cancer, even to the point of pausing adjunct therapy in order to conceive. However, menopausal hormone therapy is discouraged even years later. Non-hormonal therapy for menopausal symptoms in breast cancer survivors is available but, in some cases, estrogen-containing therapy may be worthy of consideration for quality of life in the informed patient.