Prognosis of early-onset breast cancer based on BRCA1/2 mutation status in a French population-based cohort

591 Background: The debate concerning poorer survival for patients with breast cancer (BC) carrying a BRCA1 germline mutation is unresolved, and requires additional data from population-based studies. Methods: We followed 232 women with invasive BC under age 46, ascertained prospectively through a French population-based BC registry, and tested for BRCA1/2 mutations (median follow-up: 82 months). We compared tumour characteristics and survival rates between 21 BRCA1/2 deleterious mutation carriers and 211 non-carriers. Results: As compared to sporadic tumours, BRCA1/2 tumours showed higher grade (p = 0.02), fewer ductal carcinoma in situ (p = 0.02), more frequent medullary histology (p = 0.02), more frequent negative oestrogen and progesterone receptors (p = 0.001 each). At five years, BC-specific survival, metastasis-free survival, ipsilateral recurrence-free survival and contralateral BC-free survival rates for BRCA1/2 mutation carriers were 95.0%, 94.7%, 100% and 90.0% respectively, compared with 89.6%...