Mutations in homologous recombination repair genes in patients with metastatic endometrial cancer: association with clinical characteristics and prognosis.

Objective: To evaluate the mutation rates of homologous recombination repair (HRR) genes and the impact of these mutations on the clinical characteristics of metastatic endometrial cancer (EC).

Methods: Somatic DNA from 895 patients with metastatic EC in the Memorial Sloan Kettering-Metastatic Events and Tropisms cohort was assessed for mutations in 10 HRR genes (BRCA1, BRCA2, ATM, BARD1, BRIP1, PALB2, RAD51C, RAD51D, CHEK2, and CDK12). The correlation between the mutation status of HRR genes and the clinical characteristics of patients with metastatic EC was evaluated.

Results: Somatic mutations in HRR genes were detected in 106 (11.8%) patients with metastatic EC. Compared with nonmutation carriers, a greater proportion of carriers had endometrioid carcinoma (76.4% vs. 50.3%, p<0.001). Regarding the TCGA classification, the proportions of the POLE-ultramutated (POLEmut) and mismatch repair-deficient (dMMR) subtypes were significantly greater among mutation carriers than noncarriers (20.8% vs. 0.4%, p<0.001; 34.9% vs. 11.9%, p<0.001, respectively). The carriers had a significantly lower frequency of TP53 mutations than noncarriers (25.5% vs. 54.1%, p<0.001). Fewer mutation carriers than noncarriers had intra-abdominal and lung metastases (41.5% vs. 54.2%, p=0.014; 19.8% vs. 30.3%, p=0.026, respectively). The mutation status of HRR genes did not significantly affect the overall survival of patients with metastatic EC.

Conclusion: Somatic HRR mutations are detected in 11.8% of metastatic EC. Compared with noncarriers, HRR mutation carriers in metastatic EC have higher proportions of endometrioid carcinoma, POLEmut, and dMMR subtypes, and unique metastatic patterns. However, the prognoses are similar regardless of HRR status.