21. The adjuvant treatment of breast cancer

Risk of relapse of breast cancer depends largely on tumour features: size, grade and, particularly, lymph node status. Adjuvant systemic therapies reduce risk of relapse and death, as shown in several meta-analyses. Relative risk reductions are similar across different prognostic groups but the absolute benefits are greater in those with a worse prognosis. Combination chemotherapy is superior to single agent regimens but longer duration (>6 months) gives no additional benefit compared with six months of therapy. Benefits from adjuvant chemotherapy diminish with the age of the patient. CMF type regimens have been most widely used: anthracyclines can reduce risk of relapse by 12% (an absolute survival benefit of about 3%) but with greater toxicity. Early trials of taxoids look promising but benefit was seen only in those with ER- tumours. Tamoxifen is the most extensively used endocrine adjuvant therapy, and is associated with a reduction in risk of death of 26% independent of age or menopausal status but only in those with ER+ tumours. Aromatase inhibitors are effective only in postmenopausal women and, although the early results with anastrozole look promising, long-term efficacy and toxicity studies are presently lacking, so five years of tamoxifen is standard treatment for women with ER+ tumours.