Guiding clinical decisions in incidental gallbladder cancer residual disease risk, liver resection extent, and selecting patients for adjuvant chemotherapy survival benefit

Background: Incidental gallbladder cancer (IGBC), diagnosed post-cholecystectomy for presumed benign disease, presents critical management dilemmas. This study aimed to identify preoperative and pathological risk factors for residual disease (RD) after curative-intent resection, evaluate the impact of liver resection extent on survival stratified by RD status, and define patient subgroups benefiting from adjuvant chemotherapy (ACT). Materials and Methods: A retrospective cohort study of 209 IGBC patients undergoing curative-intent resection at [Blinded for review] was analyzed. Survival was analyzed using Kaplan-Meier method with log-rank test. Prognostic factors were identified via univariate and multivariate Cox regression analyses. Factors associated with RD were assessed using logistic regression. Results: RD was present in 75 patients (35.9%) and was a strong independent predictor of worse recurrence-free survival ( HR : 2.810, 95% CI : 1.843 ~ 4.282, P < 0.001) and overall survival ( HR : 4.155, 95% CI : 2.550 ~ 6.769, P < 0.001). Independent risk factors for RD included CA19-9 > 39.0 U/ml, open cholecystectomy, primary T2 stage, primary T3 stage, perineural invasion (PNI), microvascular invasion (MVI), and station 12c lymph nodes metastasis (all P < 0.05). Among RD patients, segment IVB/V resection significantly improved median RFS (42.0 vs. 11.0 months, P < 0.001) and OS (60.0 vs. 22.0 months, P < 0.001) compared to wedge resection, while no difference was observed in non-RD patients ( P > 0.05). ACT significantly improved OS in RD patients (median not reached vs. 20.0 months, P < 0.01), with a non-significant trend towards improved RFS (40.0 vs. 11.0 months, P > 0.05), but showed non-significant trends in non-RD patients ( P > 0.05). Conclusion: RD is a critical independent prognostic factor in IGBC, predicted by elevated CA19-9, open cholecystectomy, advanced T stage, PNI/MVI, and station 12c lymph nodes metastasis. For RD patients, segment IVB/V resection and ACT both significantly improve overall survival.