Real-World Study of Regional Differences in Patient Demographics, Clinical Characteristics, and BRCA1/2 Mutation Testing in Patients with Human Epidermal Growth Factor Receptor 2-Negative Advanced Breast Cancer in the United States, Europe, and Israel

INTRODUCTION: Genetic mutations in breast cancer susceptibility gene 1 or 2 (BRCA1/2) confer a high risk for developing breast cancer; however, at least 50% of women with BRCA1/2 mutations go undiagnosed. This study evaluated differences in patient demographics, clinical characteristics, and BRCA1/2 mutation testing in the USA, European Union (EU4), and Israel in a real-world population of patients with human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC).

METHODS: This study was a retrospective analysis of data from the Adelphi Real World ABC Disease Specific Programme in the USA, EU4, and Israel. Medical oncologists completed a patient record form, which included detailed questions on demographics, clinical assessments and outcomes, and treatment history. Eligible patients were at least 18 years of age and receiving therapy for stage IIIb-IV ABC.

RESULTS: Among the 2527 study patients, 407 were from the USA, 1926 were from the EU4, and 194 were from Israel; 86% had hormone receptor-positive (HR+)/HER2- ABC and 14% had triple-negative breast cancer (TNBC). Israeli patients had a higher rate of family history of BRCA-related cancer (69%) compared with patients in the EU4 (18%; p < 0.0001) and USA (18%; p < 0.0001). Among patients with HR+/HER2- ABC, the BRCA1/2 testing rate was 99% in Israel, 37% in the EU4, and 68% in the USA (p < 0.0001 vs Israel and the EU4). The age of tested patients was significantly younger in Israel (56 years) compared with the EU4 (59 years; p = 0.016 vs Israel) and USA (64 years; p < 0.0001 vs Israel and the EU4). Among patients with TNBC, the BRCA1/2 testing rate was 100% in Israel, 78% in the EU4 (p < 0.0001 vs Israel), and 93% in the USA (p < 0.002 vs the EU4). Among tested patients, genetic counseling rates were also higher in Israel (98%) compared with the EU4 (40%; p < 0.0001) and USA (38%; p < 0.0001).

CONCLUSIONS: Testing and genetic counseling rates for BRCA1/2 mutations were very high in Israel, potentially due to the high rate of family history of BRCA-related cancer in this population and higher general awareness of genetic testing. In the EU4 and USA, overall rates of testing for BRCA1/2 mutations and genetic counseling were significantly lower compared with Israel. Given the high risk of breast cancer in BRCA1/2 mutation carriers and the efficacy of new therapies in treating ABC with a BRCA1/2 mutation, efforts should be made to improve BRCA1/2 testing rates in Europe and the USA.