CA125 kinetics as a marker for tumor progression during chemotherapy in patients with pancreatic cancer

Carbohydrate antigen 125 (CA125) is an established biomarker of ovarian cancer. However, in pancreatic cancer (PC), the biological and clinical significance of CA125 remains undefined, and the relationship between CA125 expression, tumor characteristics, and treatment outcomes remains incompletely elucidated. This retrospective study included 152 patients across three institutions who received either modified FOLFIRINOX or gemcitabine plus nab-paclitaxel between January 2014 and July 2024. The relationship between CA125 kinetics and therapeutic efficacy was analyzed, and CA125 expression was evaluated using immunohistochemistry. CA125 was detected in most primary lesions, liver and peritoneal metastases. Baseline CA125 levels were significantly associated with the number of metastatic sites and the severity of ascites. Further, 102 patients were subjected to CA125 monitoring, and their CA125 kinetics correlated with tumor response. Receiver operating characteristic curve analysis identified an optimal CA125 increase threshold for predicting progressive disease at 0.173%/day. The median progression-free survival and overall survival were 3.3 and 10.1 months, respectively, in those with increased CA125 kinetics and 9.8 and 17.3 months, respectively, in those with no increase. The results suggest that serum CA125 levels is a clinically useful biomarker in PC during chemotherapy and an increase in CA125 kinetics is an early predictor of tumor progression.