Squamous metaplasia is commonly detected in pancreatic parenchyma; however, primary pancreatic squamous cell carcinoma (SCC) is a rare malignancy with unknown incidence and unclear prognosis.
Surveillance, Epidemiology, and End Results (SEER) registries were examined identifying pancreatic SCC and adenocarcinoma cases from 2000 to 2012. Age-adjusted incidence rates were calculated. Patients with SCC versus adenocarcinoma were compared by clinical features and relative survival outcomes.
We identified 214 patients with SCC and 72,860 with adenocarcinoma. For SCC, incidence rates tripled between 2000 and 2012. Significantly higher SCC incidence rates were observed in older age groups, blacks, and males. Greater proportion of patients with SCC than those with adenocarcinoma had poorly differentiated histology (73.0% vs 43.7%, P < 0.001). In both subtypes, majority of patients had stage IV disease, 59.0% for adenocarcinoma versus 62.6% for SCC. The 1- and 2-year relative survival rate was significantly lower in patients with SCC versus adenocarcinoma. The 1-year relative survival was 14.0% (95% confidence interval, 9.5%–19.4%) for SCC, compared with 24.5% (95% confidence interval, 24.2%–24.8%) for adenocarcinoma.
Although primary pancreatic SCC is a rare neoplasm, incidence rates for this subtype are increasing. Relative to adenocarcinoma, pancreatic SCC is characterized by poorly differentiated histology and worse survival.