The prognostic role of somatic BRCA mutations in ovarian cancer: Preliminary results from an observational multicenter cohort study.

Abstract

e13674 Background: BRCA germline (gBRCA) mutations occur in 11-15% of women with unselected ovarian cancers (OC), whereas somatic BRCA (sBRCA) mutations occur in approximately 5-7% of cases. The impact of sBRCA mutations on OC outcome is still debated. Methods: With the aim to explore the prognostic role of sBRCA mutations, the BRCA mutational status of 149 non-mucinous and non-borderline OC and their clinical-pathological features were evaluated. BRCA1 and BRCA2 mutational profiles, either for sequence variants or copy number alterations, were evaluated by amplicon next-generation sequencing (NGS) technology. Results: 29 (19.5%) patients carried a gBRCA mutation (12.7% BRCA1 and 6.7% BRCA2). 26 (17.5%) patients presented a sBRCA mutation (6.7% BRCA1, 10% BRCA2, 0.6% BRCA1+BRCA2). Patients carrying a gBRCA mutation were slightly younger (57 years) than the others (60 years). The FIGO stage at the diagnosis was III-IV in 77.2% of cases, with no significant difference among subgroups. The most frequent histotype was serous for all the subgroups (93.1% in gBRCA, 84.6% in sBRCA, 77.7% in BRCA-negative, p = 0.08). 80.7% of sBRCA mutation carriers, 62.1% of gBRCA mutation carriers and 62.7% of BRCA-negative patients underwent upfront surgery (p = 0.46). 29.1% of sBRCA mutation carriers, 17.8% of gBRCA mutation carriers and 25.6% of BRCA-negative patients presented macroscopic residual disease after surgery (p = 0.68). Although non-statistically significant, gBRCA-associated OC were more likely to be platinum-sensitive (96.6%) than the other patients (92% in sBRCA and 87.1% in BRCA-negative patients). Overall, the median platinum-free interval (PFI) resulted shorter in sBRCA mutation patients compared to gBRCA and BRCA-negative patients (p = 0.051). No patient took PARP inhibitors as maintenance after the first line therapy. Also progression free survival 2 (PFS2) resulted shorter for sBRCA mutation patients (p = 0.008). Three sBRCA and 5 gBRCA mutation carriers took a PARP inhibitor as maintenance after the second line therapy. Finally, sBRCA mutated patients showed worse overall survival (OS) compared to the other subgroups (p = 0.014). Conclusions: Overall, 19.5% of OC patients presented a gBRCA mutation, while 17.5% of patients showed sBRCA mutations. sBRCA-related OC did not show significantly differences in clinical-pathological features (stage at diagnosis, histotype, time to surgery and residual after surgery). To our knowledge this is the first study showing shorter PFI, PFS2 and OS in patients carrying sBRCA mutations.