Supplementary Material for: Adjuvant Therapy in Resected Nonmetastatic Stage II–IV Gallbladder Cancer: A Generalized Propensity Score Analysis

Background: The clinical benefits and efficacies of adjuvant therapies for gallbladder cancer (GBC) have not been verified due to insufficient clinical evidence. Methods: Patients with resected nonmetastatic stage II–IV GBC were selected from the Surveillance, Epidemiology, and End Results database and distributed into nonchemotherapy and chemoradiotherapy (NCRT), chemotherapy (CT), and chemoradiotherapy (CRT) groups. Generalized propensity score and inverse probability of treatment weighting (IPTW) were used to reduce the imbalances between groups. Results: A total of 2,689 patients were enrolled, among whom 1,193 (44.4%) were classified as stage II, 1,371 (51.0%) as stage III, and 125 (4.6%) as stage IV GBC. A total of 1,703, 444, and 542 patients were placed in the NCRT, CT, and CRT groups, respectively. After the IPTW, there were no significant differences in overall survival (OS) between the 3 treatment groups (p > 0.05) in stage II GBC patients. In patients with stage III–IV GBC, the CT group exhibited a superior OS compared to the NCRT group (p < 0.001). In addition, the CRT group exhibited a superior OS compared to the CT (p < 0.001) and NCRT (p < 0.001) groups. For patients with stage III–IV tumors, a nomogram was constructed to predict the survival benefits of adjuvant therapies. Conclusion: Patients with stage II GBC may not benefit from adjuvant therapy, while patients with stage III–IV GBC were shown to benefit from chemotherapy and chemoradiotherapy. Furthermore, chemoradiotherapy exhibited a superior OS. Nevertheless, the results need to be explained in the context of retrospective studies.