Primary squamous cell carcinoma of pancreas: a population-based study

Background: Primary squamous cell carcinoma of pancreas ( SCCP) is an extremely rare pathological subtype of pancreatic cancer of ductal origin. Due to its rarity, most previous studies on SCCP focused on case reports or series and the clinio-pathological characteristics of SCCP patients remain unclear. Methods: A retrospective analysis of SCCP patients registered in the Surveillance, Epidemiology and End Results (SEER) database from 1988 to 2016 were performed, and clinical characteristics and prognosis of these patients were also further determined. Results: A total of 373 patients diagnosed with SCCP were identified. Most SCCP patients 154/243 (63.4%) SCCP patients had distant metastases. The prognosis of SCCP patients was poor with a median overall survival (mOS) of only 3.0 months (95% CI, 2.0-5.0). The 6-month, 1-year and 2-years survival rate were 25.6%, 13.2% and 5.7%, respectively. The prognosis of SCCP patients became much worse with the increasing age (P=0.01) and distant metastases (P<0.01). Cancer-directed surgery, chemotherapy and radiotherapy could significantly prolong the survival time for SCCP patients (P<0.01 for all). Multivariate Cox analysis showed that only distant metastases were independent prognostic factors of worse survival in SCCP patients (HR =1.58, 95% CI, 1.18-2.12). Conversely, both cancer-directed surgery and chemotherapy were an independent protective factor that decreased the risk of death by 66% (HR =0.18, 95% CI, 0.11-0.29) and 46% (HR =0.54, 95% CI, 0.43-0.68) for SCCP patients. Conclusions: SCCP is a rare type of pancreatic malignancies with poor prognosis. The present study could provide some useful information for future management and prospective studies for SCCP patients.