Ovarian cancer patients with methylated BRCA1 promoter detected in cfDNA (median: 57 months; 95% CI: 44.1–72.3) had a comparable survival to ovarian cancer patients with germline BRCA1 mutations (median: 62 months; 95% CI: 51.0–86.2), but a significantly longer survival than patients with unmethylated BRCA1 promoter (median 37.5 months; 95% CI: 28.0–52.3; P = 0.0019, log rank test; Fig. 4C). Here, BRCA1 is linked to ovarian cancer.