Treatment Patterns and Outcomes of Patients With Metastatic ER+/HER-2− Breast Cancer: A Multicountry Retrospective Medical Record Review

Purpose To describe treatment patterns and clinical outcomes among postmenopausal women with metastatic ER+/HER-2− breast cancer treated with ≥ 2 lines of endocrine therapy or chemotherapy in the metastatic setting. Patients and Methods Retrospective medical record review was conducted in Canada, the United Kingdom, Belgium, the Netherlands, Germany, Spain, and France. Baseline characteristics were assessed at the date of metastatic diagnosis. Time to progression (TTP) and overall survival (OS) were estimated by Kaplan-Meier analyses. Multivariable models were used to evaluate factors associated with disease progression. Results Among 901 patients, the mean (standard deviation) age at metastatic diagnosis was 62.7 (9.7) years; 67.26% were initially diagnosed with metastatic disease, 66.37% had visceral disease, and 25.86% had bone metastasis only. Two-thirds of patients received endocrine therapy for first-line treatment. Fifty-nine percent received endocrine therapy, and 37.18% received chemotherapy for second-line treatment. The most common reason for stopping treatment was disease progression. Median (95% confidence interval [CI]) TTP on first-line endocrine treatment was 11.3 (10.7-12.2) months and 7.0 (6.3-7.9) months on chemotherapy. Median (95% CI) TTP on second-line endocrine therapy was 8.1 (7.5-9.1) months and 6.1 (5.4-6.8) months on chemotherapy. Median (95% CI) OS was 68.6 (52.2-83.7) months after first-line endocrine therapy and 39.7 (34.5-48.7) months after chemotherapy. Conclusion Patients prescribed endocrine therapy had longer TTP and OS than patients prescribed chemotherapy in the first- and second-line settings. Disease progression was less than a year regardless of treatment type and line of therapy, indicating a need for treatments that delay progression without affecting quality of life among these patients.