Treatment Patterns, Safety, and Patient Reported Outcomes among Adult Women with Human Epidermal Growth Factor Receptor 2-Negative Advanced Breast Cancer with or without, or with Unknown, BRCA1/2 Mutation(s): Results of a Real-World Study from the United States, United Kingdom, and four EU Countries

INTRODUCTION: This real-world study assessed the breast cancer susceptibility gene 1 or 2 mutation (BRCA1/2mut) status on treatment patterns, safety, and patient-reported outcomes (PROs) in women with human epidermal growth factor receptor 2-negative (HER2−) advanced breast cancer (ABC) in the USA, the UK, and EU4 countries. METHODS: Oncologists abstracted data from medical charts of adult women who presented with HER2− ABC from February to May 2015 and from March to July 2017. Data were collected using a physician-reported form and a patient-reported form, which included questions on breast cancer history/treatment and questions from PRO instruments (EuroQol 5-Dimensions 3-Levels [EQ-5D-3L], Brief Pain Inventory [BPI], European Organisation for Research and Treatment of Cancer [EORTC] Quality of Life Questionnaire Core 30 and its breast cancer module). RESULTS: In total, 742 oncologists provided data for 6,161 patients; 27.5% were tested for BRCA1/2mut. Out of the total patient population, 3.8% had BRCA1/2mut, 16.6% BRCA1/2 wild-type (BRCA1/2wt), and 79.5% were BRCA1/2 unknown (BRCA1/2unk). Hormone receptor-positive (HR+)/HER2− ABC was more frequent within the BRCA1/2wt versus BRCA1/2mut group and triple-negative breast cancer (TNBC) within the BRCA1/2mut versus BRCA1/2wt group. More patients with HR+/HER2− ABC with BRCA1/2mut received chemotherapy (with or without targeted or endocrine therapy) versus BRCA1/2wt (66.0% vs. 50.4%; p < 0.01); more patients had ≥1 AE (58.0% vs. 39.1%; p < 0.001). Among patients with BRCA1/2mut versus BRCA1/2wt, a significantly higher proportion had some problems or worse pain discomfort (p = 0.021) and anxiety/depression (p = 0.007) as measured by the EQ-5D-3L; role functioning (p < 0.01) and dyspnea (p < 0.05) measured by EORTC were worse with BRCA1/2mut. Pain scores by BPI were similar between groups. CONCLUSIONS: In patients with HER2− ABC in the real-world setting, more patients with BRCA1/2mut had TNBC; received chemotherapy; had >1 AE; and experienced increased discomfort, anxiety, and dyspnea and diminished role functioning versus patients with BRCA1/2wt.