Introduction/Background Assessment of multigene panel testing (MPT) effectiveness in ovarian cancer (OC) is crucial, accompanied by exploration of potential correlations between germline likely pathogenic (C4) and pathogenic (C5) variants with clinical presentation and prognosis.

Methodology Retrospective analysis of OC patients diagnosed at IRCCS San Matteo Foundation, Pavia between 2009 and 2022 was performed. From 2015 onwards, all tested patients underwent MPT as part of our routine clinical practice.

Results Among 377 OC patients, 68.17% (n=257) underwent genetic testing, with 96 (37.36%) undergoing BRCA testing and 161 (62.7%) MPT. Of those, C4-C5 variants were identified in 40 (41.66%) women in the BRCA testing group, and 50 (31.05%) in the MPT group. In the overall population, 64 (24.9%) patients carried BRCA C4-C5 variants, while 26 (10.12%) carried mutations in genes other than BRCA. The introduction of MPT significantly improved the detection rate for C4-C5 germline mutations (14.9% vs 31.05%; p=0.0067). Seventeen non-BRCA susceptibility genes were identified, with BRIP1, ERCC2, RAD51C, D, PALB2, and CHEK2 being the most frequently detected. The mean age at diagnosis was significantly younger in BRCA carriers (54 years) compared to both non-BRCA (61 years, p=0.007322) and wild-type (WT) population (59 years, p=0.000767). No significant differences were observed in stage, histotype, therapeutic approach, and prognosis according to the genetic profile. One-third of carriers of C4-C5 BRCA (n=23, 36%) and non-BRCA variants (n=9, 35%) had additional primary tumors, compared to only 16% (n=27) in the WT population. A positive family history for BRCAness-related tumors was significantly associated with the presence of C4-C5 germline mutations (p=0.0153) in both BRCA (53.1%) and non-BRCA (53.8%) carriers compared to WT women (34.7%).

Conclusion MPT in OC increased germline pathogenic variants detection rate, with important clinical applications for both patients and their families. Further investigations are needed to understand the implications for response to targeted therapies and prognosis.

Disclosures None.