Real-World Study of Regional Differences in Patient Demographics, Clinical Characteristics, and BRCA1/2 Mutation Testing in Patients with Human Epidermal Growth Factor Receptor2-Negative Advanced Breast Cancer in the United States, Europe, and Israel.

Abstract

Genetic mutations in breast cancer susceptibility gene1 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 receptor2-negative (HER2-) advanced breast cancer (ABC). 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 18years of age and receiving therapy for stageIIIb-IV ABC. 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 (56years) compared with the EU4 (59years; p = 0.016 vs Israel) and USA (64years; 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). Testing and genetic counseling ratesfor 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.