The Diagnostic Performance of CA 125, CT Scan and Combination of CA 125 With CT Scan in Extra-Uterine Extension, Including Intra-Abdominal Lymph Node Metastasis in Apparently Early-Staged Endometrial Cancer Patients

Abstract

Study Objective: To evaluate the diagnostic performance of pretreatment serum CA125 level, computerized tomographic (CT) scan, and their combination in detecting extra-uterine disease, including pelvic lymph node metastasis, among patients with apparently early-stage endometrial cancer. Design: Retrospective cross-sectional study. Setting: Ramathibodi Hospital, Mahidol University, Bangkok, Thailand. Patients: A total of 399 patients with apparently early-stage endometrial cancer who underwent surgical staging with lymphadenectomy between January 2016 and July 2024 and had both preoperative CA125 levels and CT scans available for review. Interventions: Preoperative serum CA125 levels were analyzed, and CT scans were independently reviewed by radiologists blinded to clinical and laboratory data. Diagnostic performance was assessed against final pathological findings. Measurements and Main Results: The performance of CA125, CT scan, and their combination was evaluated for predicting extra-uterine and pelvic nodal disease. A CA125 cutoff >35 U/mL combined with CT scan demonstrated acceptable diagnostic ability, with an AUC-ROC of 0.792 (95% CI, 0.737–0.848) for detecting extra-uterine metastasis and 0.834 (95% CI, 0.776–0.892) for pelvic lymph node metastasis. When an optimized CA125 cutoff of ≥28.35 U/mL was combined with a CT scan, diagnostic performance for pelvic nodal involvement was markedly enhanced, achieving an AUC-ROC of 0.909 (95% CI, 0.888–0.929), reflecting excellent accuracy. These findings suggest that using both biomarkers and imaging synergistically provides superior predictive value compared with either modality alone. Conclusion: Pretreatment serum CA125 combined with CT scan yields high diagnostic accuracy for detecting extra-uterine disease and pelvic lymph node metastasis in apparently early-stage endometrial cancer. This approach may guide preoperative counseling, optimize surgical planning, and support the adoption of minimally invasive strategies in suitable patients.