Dynamic monitoring of immunoglobulin G as a prognostic indicator after curative resection in high-risk stage II–III colorectal cancer: a retrospective cohort study

Background: Reliable markers for predicting postoperative recurrence in high-risk stage II-III colorectal cancer remain limited. Dynamic changes in immunoglobulin G (IgG) may provide prognostic information beyond carcinoembryonic antigen (CEA). Methods: This single-centre retrospective cohort study included 192 patients with high-risk stage II or III colorectal cancer who underwent curative resection between January 2021 and June 2023. The study evaluated whether dynamic postoperative monitoring of serum IgG predicts 2-year disease-free survival (DFS) compared with CEA. Serial IgG and CEA measurements within 24 months were categorised as favourable or unfavourable trajectories based on predefined thresholds and temporal trends. Patients were further stratified into four groups according to combined IgG and CEA dynamics. Survival was assessed using Kaplan-Meier analysis and Cox regression models. Results: Among 192 eligible patients, 60 (31.3%) experienced recurrence or death within 2 years. Unfavourable IgG trajectories (n=82) were associated with significantly lower 2-year DFS than favourable trajectories (55% [95% CI 44-65] vs 82% [95% CI 73-88], log-rank P