Longitudinal Effects of Adjuvant Endocrine Therapy on the Quality of Life of Post-menopausal Women with Non-metastatic ER+ Breast Cancer: A Systematic Review

Background Anti-estrogen (ER) endocrine therapy is an effective treatment strategy in reducing breast cancer mortality. This therapy has a better therapeutic index than chemotherapy but can still affect patients’ quality of life (QOL) over time. Objective The objectives of this systematic review were to (1) describe QOL instruments used in ER-positive (ER+) non-metastatic breast cancer trials and (2) document the longitudinal effects of adjuvant endocrine therapy on the QOL of post-menopausal women with ER+ non-metastatic breast cancer. Methods We searched three electronic bibliographic databases for articles published from inception to October 2017 that described (1) a randomized controlled trial (RCT) of non-metastatic breast cancer containing an adjuvant endocrine regimen in at least one arm; (2) the use of a patient self-report measure assessing general or breast cancer-specific QOL; and (3) QOL outcomes at multiple time points during follow-up of at least 5 years. All included trials were independently evaluated by two reviewers, and data were extracted using standardized forms. Results In total, 13 studies met our inclusion criteria and were assessed in this review. The quality of the trials was reasonably good. The top three most commonly used QOL instruments in the trials were the Functional Assessment of Cancer Therapy/Functional Assessment of Chronic Illness Therapy, the Short Form-36 and the Menopause-Specific Quality of Life. Most studies found no differences between tamoxifen and aromatase inhibitor groups in terms of global QOL. QOL data affected treatment regimen recommendations in a few cases. A meta-analysis was not feasible because the RCTs included in our review varied in terms of sample size, comparators, QOL instrument used, and timing of QOL measurement. Additionally, as no search strategy has perfect sensitivity, specificity and accuracy, there is always a chance that potentially relevant articles were missed. Conclusion This systematic review suggests that the QOL of post-menopausal women is unlikely to be adversely affected by long-term use of adjuvant endocrine therapy. Efforts are needed to improve the quality of QOL reporting in clinical trials.