138 - The Prognostic Value of Pretreatment Carbohydrate Antigen 125 Level in Cervical Cancer Patients Treated with Definitive Radiotherapy or Concurrent Chemoradiotherapy

D. Liu¹, W. Wang¹, X. Liu², Z. Zeng², C. Wang³, X. Li¹, and K. Hu²; ¹Department of Radiation Oncology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, ²Department of Radiation Oncology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China, ³Department of radiation oncology, Peking Union Medical College Hospital. Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China

Purpose/Objective(s): Carbohydrate antigen 125 (CA125) is a widely used tumor marker, but its relationship with the prognosis of cervical cancer is little known. The study aims to investigate the prognostic value of pretreatment CA125 levels in patients with cervical cancer receiving definitive radiotherapy or concurrent chemoradiotherapy (CCRT), to identify the optimal pretreatment CA125 cutoff value for predicting treatment failure, and to explore its association with survival outcomes. Materials/

Methods: A total of 645 patients (543 squamous cell carcinoma [SCC] patients, 85 adenocarcinoma [ADC] patients, and 17 others) satisfying the eligibility criteria treated between 2007 and 2016 were included, with a median follow-up duration of 60.2 months. The primary endpoint was disease-free survival (DFS), and the secondary endpoints included overall survival (OS) and local control (LC). The optimal cutoff value for pretreatment CA125 levels was verified by the receiver operating characteristic (ROC) curve. Five-year OS, DFS, and LC rates were evaluated utilizing the Kaplan-Meier method. The log-rank test and Cox proportional hazards model were implemented to recognize independent prognostic predictors. After analyzing the whole cohort, we further conducted analyses of both SCC and ADC subgroups. All statistical analyses were performed using R software.
Results: In the whole cohort, the optimal pretreatment CA125 cutoff value was 26.1 U/mL, with elevated levels presenting significantly inferior five-year DFS (59.4% vs. 80.6%, P < 0.001), OS (66.1% vs. 86.2%, P < 0.001), and LC (75.4% vs. 91.4%, P < 0.001) compared to those with lower levels. Univariate and multivariate analyses identified the higher pretreatment CA125 level as an independent predictor of treatment failure (hazard ratio [HR], 2.16 [1.57-2.98]; P < 0.001). Subgroup analysis yielded similar results. For the SCC subgroup, the optimal pretreatment CA125 cutoff value was 25.6 U/mL, with higher levels indicating poorer five-year DFS (64.9% vs. 81.7%, P < 0.001), OS (67.4% vs. 87.9%, P < 0.001), and LC (79.6% vs. 91.9%, P < 0.001). Pretreatment CA125 level independently predicted treatment failure (HR, 1.85 [1.27, 2.68], P = 0.001). In the ADC subgroup, the optimal pretreatment CA125 cutoff value was 27.6 U/mL, with higher CA125 levels associated with worse five-year DFS (41.8% vs. 75.0%, P = 0.003) and LC (60.0% vs. 86.9%, P = 0.003), and a trend towards decreased OS (65.0% vs. 75.9%, P = 0.09) was observed. Pretreatment CA125 level remained an independent predictor of treatment failure (HR, 2.51 [1.11, 5.68], P = 0.03).
Conclusion: Pretreatment CA125 levels are associated with treatment outcomes in cervical cancer patients receiving definitive radiotherapy or CCRT. Elevated levels indicate unfavorable treatment outcomes, with the analysis revealing applicability across both SCC and ADC subtypes. This study underscores the potential of pretreatment CA125 as a valuable prognostic marker in cervical cancer management.