[Association analysis on BRCA gene functional domain mutations and prognosis in patients with ovarian epithelial carcinoma and fallopian tube carcinoma].

Objective: To analyze the characteristics of BRCA gene mutations in patients with ovarian epithelial carcinoma and fallopian tube carcinoma, and to investigate the impact of mutations in the functional domains of the BRCA genes on the prognosis of patients. Methods: This research collected a total of 273 patients diagnosed with primary ovarian epithelial carcinoma or fallopian tube carcinoma by pathological examination at the First Affiliated Hospital of Nanjing Medical University between January 2009 and December 2023.Data on their BRCA gene mutation status, clinicopathological data, and follow-up information were collected. A retrospective analysis was conducted to evaluate the association between BRCA gene mutations and patients' prognosis, including progression free survival (PFS) and overall survival (OS) time. Results: Among the 273 patients with ovarian or fallopian tube carcinoma, 101 cases (37.0%, 101/273) were positive for BRCA gene mutations (BRCA-positive group), while 172 cases (63.0%, 172/273) were negative for BRCA gene mutations (BRCA-negative group). (1) Clinicopathological characteristics: compared with the BRCA-negative group, the BRCA-positive group had a younger age at diagnosis, lower proportion of postmenopausal status, and lower recurrence rate (all P<0.05). Additionally, the BRCA-positive group showed a higher prevalence of family history of gynecological malignancies and a higher rate of no visible residual disease (R0) resection, all with statistical significance (all P<0.05). (2) Characteristics of BRCA gene mutations: among the 101 BRCA-positive patients, 74 cases (27.1%, 74/273) had BRCA1 gene mutations, 26 cases (9.5%, 26/273) had BRCA2 gene mutations, and 1 case (0.4%, 1/273) had indeterminate mutation records. According to the American College of Medical Genetics and Genomics (ACMG) 2015 guideline, mutations of uncertain significance accounted for 22.8% (23/101), likely pathogenic mutations accounted for 10.9% (11/101), and pathogenic mutations accounted for 59.4% (60/101), with 5.9% (6/101) unclassifiable. BRCA1 and BRCA2 genes have three (RING, DBD, BRCT) and two (RAD51-BD, DBD) major functional domains, respectively. Among the 89 BRCA-positive patients with detailed domain mutation data, the overall domain mutation rate was 40.4% (36/89), distributed as follows: DBD 14.6% (13/89), BRCT 12.4% (11/89), RING 4.5% (4/89), and RAD51-BD 9.0% (8/89). (3) Association between BRCA gene functional domain mutations and prognosis: among 77 patients with advanced stage (Ⅲ-Ⅳ) ovarian epithelial carcinoma in the BRCA-positive group with functional domain mutation data, the median PFS time was significantly longer in the 31 patients with domain mutations compared to the 46 patients with non-domain mutations (not reached during the follow-up period, vs 26.0 months; P=0.035). However, there was no significant difference in median OS time between the two groups (not reached during the follow-up period, vs 67.0 months; P=0.513). Median PFS time was longer in 13 patients with mutations in the DBD functional domain than that in 64 patients with mutations outside the DBD functional domain (not reached during the follow-up period, vs 28.0 months; P=0.042), whereas there was no significant difference in the comparison of median OS time between the two groups (not reached during the follow-up period, vs 67.0 months; P=0.321). (4) Association between BRCA gene functional domain mutations and efficacy of poly adenosine diphosphate ribose polymerase inhibitor (PARPi) maintenance therapy: among 51 advanced stage ovarian epithelial carcinoma patients who received PARPi maintenance therapy in the BRCA-positive group, 20 patients with domain mutations demonstrated significantly longer median PFS time compared to 31 patients with non-domain mutations (not reached during the follow-up period, vs 31.0 months; P=0.039). However, no significant difference was observed in median OS time between the two groups (not reached during the follow-up period, vs 53.0 months; P=0.178). PARPi maintenance therapy was more effective in the 9 patients with mutations in the DBD functional domain than that in the 42 patients with mutations located outside the DBD structural domain, with significant differences observed in both median PFS time (both not reached during the follow-up period; P=0.007) and median OS time (both not reached during the follow-up period; P=0.037). In contrast, patients with mutations in the BRCT or RAD51-BD domains showed no significant differences in either median PFS or OS time compared to patients with mutations outside these domains (all P>0.05). Conclusions: Patients with ovarian epithelial carcinoma and fallopian tube carcinoma who harbor BRCA functional domain mutations exhibit significantly longer median PFS time compared to those with non-domain mutations. Moreover, among patients received PARPi maintenance therapy, those with mutations in the DBD domain have a better median PFS and OS time benefit.