Mismatch Repair, p53, and L1 Cell Adhesion Molecule States Influence the Response to Chemotherapy in Advanced and Recurrent Endometrial Cancer

(1) Background: This study aimed to identify the recurrence and survival rates according to the mismatch repair (MMR), p53, and L1 cell adhesion molecule (L1CAM) states in patients with advanced and recurrent endometrial cancer receiving systemic chemotherapy.; (2) Methods: This single-center retrospective cohort study included chemotherapy-naïve patients (n=156) with advanced-stage (III/IV) or recurrent endometrial cancer who were administered chemotherapy as adjuvant therapy (n=112) or first-line palliative treatment (n=44) between January 2015 and June 2022. MMR and p53 states were assessed using PCR, and L1CAM was tested using immunohistochemistry in the no specific molecular profile (NSMP) group. The primary outcomes were progression-free survival (PFS) and overall survival (OS).; (3) Results: Of the 156 patients, 62 (39.7%), 53 (34.0%), and 41 (26.3%) had NSMP, abnormal p53 (p53abn), and an MMR deficiency (MMR-D), respectively. PFS and OS were longest in MMR-D, followed by NSMP, and were the least in p53abn tumors (PFS: p=0.0006, OS: p=0.0013). After NSMP was classified according to positive or negative L1CAM status, the L1CAM-negative group exhibited significantly lower survival rates than the L1CAM-positive group (PFS: p=0.0001, OS: p=0.0027); p53abn tumors were independent prognostic factors for poor PFS (p=0.039 on the multivariable analysis).; (4) Conclusions: In chemotherapy-naïve patients with advanced and recurrent endometrial cancer, the best prognosis after chemotherapy was obtained using MMR-D, followed by NSMP and p53abn tumors. The L1CAM status is a useful new marker for stratifying NSMP in advanced and recurrent patients.