Clinical outcomes of female breast cancer according to BRCA mutation status.

BACKGROUND: To investigate breast cancer prognosis (disease-free (DFS) and overall survival (OS)) among carriers of germline BRCA mutations (BRCAm) in Denmark.

METHODS: We identified all women in Central and Northern Denmark diagnosed with breast cancer during 2004-2011. We retrieved information on germline BRCAm testing from Clinical Genetics departments and clinical/treatment characteristics from population-based medical registries. Follow-up for recurrence, new primary cancer, and mortality extended from 180days after diagnosis until 31/12/2012. We estimated median DFS and OS and five-year cumulative incidence and incidence rates (IR/1000 person-years), and 95% confidence intervals (95% CI), for each outcome.

RESULTS: Among 9874 patients, 523 (5%) underwent BRCA testing-90 were BRCAm carriers, 433 were BRCA wildtype (BRCAwt). Compared with BRCAwt women, BRCAm carriers were younger, had lower stage, and ER- and HER2- tumors. Median time from diagnosis to BRCA testing was 0.91 years and 1.3 years in BRCAm and BRCAwt women; median follow-up to first event was 3.9 and 3.4 years, respectively. Five-year DFS and OS were higher in BRCAm than BRCAwt women: 88% (95%CI=78.3-93.5) vs. 75.3% (95%CI=70.2-79.6) and 97.8% (95%CI=91.4-99.4) vs 92.2% (95%CI=88.5-94.7), respectively. Five-year IRs of recurrence were 36.7/1000 person-years (95%CI=15.8-72.2) in the BRCAm cohort vs. 58.4 (95%CI=42.9-77.6) in the BRCAwt cohort.

CONCLUSIONS: BRCAm carriers may have a better prognosis than BRCAwt women. However, limited testing conducted mainly during follow-up, yielded low numbers for precise estimations, and may be attributable to selection bias.