Dynamic changes in serum carcinoembryonic antigen independently predict disease-free

This study aimed to evaluate the predictive value of serum carcinoembryonic antigen (CEA) changes for treatment response in colorectal cancer(CRC) patients receiving CAPOX chemotherapy, providing a reliable indicator for clinical efficacy monitoring.

Clinical data of CRC patients who first received the CAPOX regimen at the Sixth Affiliated Hospital of Sun Yat-sen University between January 1, 2016 and January 31, 2026 were retrospectively collected. Parameters included operation date, chemotherapy administration dates, disease progression (PD) time, preoperative CEA, baseline CEA before chemotherapy, CEA before each cycle, and CEA within three months post-chemotherapy. Disease-free survival (DFS) was calculated. Patients were divided into Group 1: CEA is in the normal range (all values are ≤ 5ng/ml); Group 2: Decreasing or normalization type (not Group 1, and the last valid value ≤ 5ng/ml, or a decrease of ≥20% compared to the individual's previous peak); Group 3: Persistent or new-onset abnormal type (the rest, that is, the last value > 5 and the decrease from the peak value < 20%). Survival curves were plotted using the Kaplan-Meier method, and multivariate Cox regression was used to assess correlations between CEA changes, treatment efficacy, and DFS.

Median DFS (mDFS) was 55.668 months (95% CI: 51.511-58.826) in Group 1 (n=84); 42.271 months (95% CI: 35.438-49.104) in Group 2 (n=47) and 19.980 months (95% CI: 11.198-28.762) in Group 3 (n=11).

Dynamic changes in serum CEA have good predictive value for the efficacy of CAPOX chemotherapy in CRC. This predictive value is primarily significant in TNM Stage III patients and serve as an independent prognostic factor. Patients with decreased or persistently normal CEA levels have a better prognosis.