Abstract
This study aimed to validate the Proactive Molecular Risk Classifier for Endometrial Cancer, a modified version of The Cancer Genome Atlas, using data from 184 patients with endometrial cancer (median age: 57.5 years; median follow-up period: 109 months) who had undergone radical surgery (including systemic lymphadenectomy) and subsequent adjuvant chemotherapy (patients with intermediate or high recurrence risk) from 2003 to 2015. Tissue microarrays were prepared from surgical specimens and classified using the conventional clinical risk classifier. Immunohistochemistry was used to detect mismatch repair proteins, L1 cell adhesion molecule, and p53. Direct sequencing was used to identify hotspot mutations in the polymerase-epsilon gene. Forty-five patients were identified as having high L1 cell adhesion molecule expression, 41 as low risk, 34 as mismatch repair-deficient, 13 as polymerase-epsilon gene-mutated, five as having abnormal p53, and 46 as other. Patients were stratified into significantly different prognostic groups (p < 0.0001): favorable (low risk and polymerase-epsilon gene-mutated), intermediate (mismatch repair-deficient and other), and unfavorable (high L1 cell adhesion molecule expression and abnormal p53) with 5-year disease-specific survival rates of 100%, 93.8%, and 75.1%, respectively (Kaplan-Meier method). The combination of conventional recurrent risk classification, sequencing for polymerase-epsilon gene mutations and immunohistochemistry for L1 cell adhesion molecule, p53, and mismatch repair proteins can be used to determine the prognoses of patients with endometrial cancer.