Navigating the Challenges of Endocrine Treatments in Premenopausal Women with ER-Positive Early Breast Cancer

Endocrine therapy is a key component of adjuvant treatment for premenopausal patients with endocrine-responsive tumors. It is commonly well tolerated, although side effects are a main concern in the selection of treatment options. Tamoxifen is still considered an adequate endocrine therapy in a large group of premenopausal patients (e.g. lower-risk patient, presence of co-morbidities, patient preference). Results of the SOFT and TEXT trials addressing new adjuvant endocrine treatment options in premenopausal patients were recently presented. Overall, in the SOFT study the premenopausal population did not benefit from the addition of ovarian function suppression (OFS). Nevertheless, for women at sufficient risk of recurrence to receive adjuvant chemotherapy and who maintained premenopausal estradiol, the addition of OFS to tamoxifen reduced the risk of recurrence. The magnitude of the effect was larger in younger patients. Moreover, in the SOFT and TEXT trials, adjuvant treatment with exemestane plus OFS, as compared with tamoxifen plus OFS, significantly improved disease-free survival, breast cancer-free interval and distant disease-free survival. However, premenopausal patients include heterogeneous subsets of women and tumors where costs and benefits of adjuvant endocrine therapy should be properly weighted. Issues specific for premenopausal patients, related to desire for pregnancy, family planning, safety, quality of life and subjective side effects, should be a priority in the therapeutic algorithm. Therefore, selecting the best-tolerated agent can enhance adherence to therapies and reduce the impact on quality of life and health status for these younger patients.