Comparison of carcinosarcoma and adenocarcinoma of the gallbladder: a study based on SEER population for propensity matching and nomogram analysis.

Background: Carcinosarcoma of the gallbladder (CSGB) is an uncommon malignancy, and limited literature is available on its clinicopathological features, prognosis, and treatment options.

Methods: Using the SEER database, we selected 7634 gallbladder adenocarcinoma patients (diagnosed from 2004 to 2015) and 58 carcinosarcoma of the gallbladder patients (diagnosed from 1988 to 2019) based on predetermined criteria. We compared the overall survival (OS) and cancer-specific survival (CSS) before and after propensity score matching in two groups. Cox univariate and multivariate analyses were performed, and a nomogram was further generated to investigate the impact of clinical and pathological variables on the survival of patients with CSGB. Finally, we evaluated the effect of different treatment modalities on the overall survival of CSGB patients.

Results: Notably, CSGB patients had larger tumors and underwent surgery more frequently than gallbladder adenocarcinoma patients, with lower rates of deeper tumor infiltrates, and lymph node infiltrates. Conversely, gallbladder adenocarcinoma patients had a higher proportion of AJCC staging (III-IV). Despite these differences, no significant differences were found in OS and CSS between the two groups before and after propensity score matching. For CSGB patients, AJCC staging, surgery and tumor size were significant prognostic factors, while treatment modalities such as surgery combined with chemotherapy, or combined radiochemotherapy, as well as radical resection, did not significantly prolong patient survival.

Conclusion: No significant difference was found in survival rates between CSGB and gallbladder adenocarcinoma patients, while radical surgery and different combined treatment modalities did not provide significant survival benefits.