Molecular classification and association with survival outcomes in high-intermediate and high-risk early-stage endometrial cancers: Ancillary analysis of GOG-0249.

OBJECTIVE

Determine whether mismatch repair (MMR) and p53 expression predict recurrence-free survival (RFS) and overall survival (OS) in early-stage endometrial cancer (EC) patients treated with vaginal cuff brachytherapy plus chemotherapy (VCB/C) versus pelvic radiation therapy (RT).

METHODS

In the GOG-0249 trial, 601 patients with high-intermediate risk (HIR) early-stage EC were randomized to VCB/C (carboplatin/paclitaxel for 3 cycles) or pelvic RT. Molecular subgroups, deficient MMR (dMMR), p53 wildtype (p53wt), p53 abnormal (p53abn), were determined by immunohistochemistry. Five-year RFS and OS were analyzed using Kaplan-Meier curves and Cox proportional hazards models, adjusting for lymphadenectomy, planned VCB, and treatment group.

RESULTS

Among 315 patients, 23.5% had EC exhibiting p53abn expression, 32.1% had dMMR, and 44.4% had p53wt. p53abn EC was associated with older age (p = 0.004), serous histology (p < 0.001), lymphadenectomy (p = 0.02), and planned VCB (p < 0.001). Five-year RFS and OS were worse in patients with p53abn cancers, 58.7% [Hazard Ratio (HR) = 4.0 (95% Confidence Interval (CI): 2.1-7.5)] and 70.7% [HR = 9.4 (95%CI: 3.8-23.6)] and dMMR cancers 74.4% [HR = 1.8 (95%CI: 0.9-3.3)] and 84.3% [HR = 3.0 (95%CI: 1.2-7.8)] compared to those with p53wt (referent) (83.4% and 95.3%) (p < 0.001). The RFS (p = 0.7) and OS (p = 0.8) rates did not differ by treatment within molecular subgroups.

CONCLUSION

Molecular classification is prognostic for survival outcomes in patients with stage I-II HIR/high-risk EC. Patients with p53abn cancers seem to have the highest risk of relapse and death. Molecular subgroups do not appear to predict benefit from VCB/C as compared to pelvic RT. Novel therapeutic approaches are needed, especially for those with dMMR and p53abn expressing cancers.