Extended endocrine therapy in early breast cancer: how long and who for?

Endocrine therapy for early stage breast cancer is currently in a state of flux with much uncertainty about choice of agents and duration of therapy. The standard treatment span of 5 years usually incorporates an aromatase inhibitor in the majority of postmenopausal patients. Hormonal therapy has a cytostatic action that provides a biological rationale for continuing treatment for more prolonged periods to reduce risk of late recurrence in estrogen receptor-positive disease. Several trials of extended endocrine therapy for periods varying from 7.5 to 10 years have shown mixed results for gains in disease-free survival. The challenge is to assimilate available data and apply clinical judgment to tailor therapies taking account of intrinsic risk of disease recurrence, patient preference, tolerability to date, and co-morbidities.