Comparative study of sarcomatoid carcinoma and carcinosarcoma of the pancreas: a population-based study

Background: Sarcomatoid carcinoma (SCP) and carcinosarcoma (CSP) of the pancreas are extremely rare entities and little is known about their characteristics. Using a population-based cancer registry, we aimed at improving our understanding of these entities with a focus on the comparison between these two entities. Methods: Patients with SCP or CSP were identified through the Surveillance Epidemiology and End Results (SEER) database. Demographic and clinical characteristics were collected and compared. Survival was compared using the Kaplan-Meier method and analyzed using the log-rank test and Cox proportional hazards models. Results: A total of 85 patients with SCP and 32 patients with CSP were included in the study. There was no difference in the patient age, race distribution, year of diagnosis, primary site, tumor size, tumor stage, receipt of chemotherapy and receipt of radiotherapy between the two groups. However, more patients with CSP received surgical treatment (P<0.001) when compared to patients with SCP. Overall survival was comparable between the two groups (P=0.562) with a 1-year survival rate of 20.8% and 22.2% for SCP and CSP, respectively. Multivariate analysis showed that surgical resection was independent prognostic factor of both SCP (HR: 0.34, P=0.017) and CSP (HR: 0.17, P=0.017). Chemotherapy was a prognostic factor of CSP in univariate analysis, but not of SCP. Conclusions: SCP and CSP are rare malignant tumors of the pancreas with a dismal prognosis. Surgical resection was the common prognostic factor and was recommended when possible.