Endocrine therapy is a type of treatment, that acts to inhibit the growth of breast cancer cells which have hormone receptors. It does this by blocking either the production of female hormones or the ability of hormones to interact with receptors on cancer cells.
Endocrine therapies include:
- ovarian suppression/ablation, e.g. luteinising hormone-releasing hormone agonists (goserelin, buserelin), ovarian irradiation, and surgical oophorectomy
- selective oestrogen receptor modulators, e.g. tamoxifen
- selective oestrogen receptor downregulators, e.g. fulvestrant
- progestins, e.g. megestrol acetate and medroxyprogesterone
- aromatase inhibitors, e.g. anastrozole, exemestane, letrozole.
This guideline is based on a meta-analysis2 and an evidence review.3 The meta-analysis is about the use of endocrine therapy in pre-menopausal women with hormone receptor-positive advanced breast cancer. The evidence review is about the use of endocrine therapy in post-menopausal women with hormone receptor-positive advanced breast cancer. The evidence is not specific to women with metastatic (stage IV) breast cancer. While the majority of women had stage IV metastatic disease, a small number of women with locally advanced disease and/or locoregional recurrence were included in the trials. In the majority of trials, women with tumours of unknown hormone receptor status were also eligible for participation.
A previous Cochrane review (2003)4 investigating randomised trials comparing the effects of chemotherapy alone with endocrine therapy alone in women with metastatic breast cancer found that endocrine therapy is the preferred first-line treatment for women with hormone receptor-positive breast cancer, except in the presence of rapidly progressive disease. The review also found that the incidence of adverse events is less frequent with endocrine therapy compared with chemotherapy.