BRCA1 and ovarian cancer: Comparing primary and recurrent ovarian cancers, it was shown that 13 out of 46 recurrent HGSOCs (28.3%, 95% CI 17.3–42.6%) had a secondary mutation and 2 out of 64 primary HGSOCs (3.1%, 95% CI 1.0–10.7%) in germline BRCA1/2 mutation carriers.