Adjuvant Chemoradiotherapy Versus Chemotherapy Alone After Resection of Gallbladder Carcinoma: A Real-World, IPTW-Based Cohort Study.

Purpose: To compare overall survival (OS) and disease-free survival (DFS) in patients with advanced resectable gallbladder carcinoma (GBC) receiving radical resection followed by chemoradiotherapy (S+CRT) or chemotherapy alone (S+CT).

Methods and materials: This real-world study included 239 patients (pT2-4, N0-2, M0) treated between February 2017 and November 2021. Inverse probability of treatment weighting (IPTW) was applied to balance baseline variables between S+CRT and S+CT groups. Kaplan-Meier analysis and Cox regression were used to evaluate survival. Predefined subgroups analyses were conducted for 77 patients with incidental GBC and 94 patients with nodal metastasis (pN+). Adverse events and recurrence patterns were recorded for the entire cohort.

Results: Median follow-up was 57.4 months. IPTW created 472.6 weighted patients with well-balanced characteristics. S+CRT was associated with higher OS and DFS at 1, 3, and 5 years compared to S+CT (OS: 90.5%, 71.9%, 65.8% vs. 81.6%, 56.1%, 50.1%; DFS: 77.8%, 65.1%, 57.7% vs. 63.1%, 45.3%, 42.6%). Median OS and DFS were not reached in the S+CRT group. In the incidental GBC subgroup, survival differences were not statistically significant overall, but a landmark analysis beyond 24 months revealed improved OS favoring S+CRT (P=0.011). Similarly, in the subgroup with nodal metastasis (pN+), adjuvant CRT was associated with a significant improvement in DFS.

Conclusions: Postoperative CRT significantly improved OS and DFS in balanced patients with stage II-IV GBC. A delayed OS benefit was observed in patients with incidental GBC, while patients with nodal metastasis also experienced significantly improved DFS. Although intrahepatic recurrence remained predominant, CRT notably reduced local failures without significantly increasing treatment-related toxicity.