415 patients with adenosquamous carcinoma of the pancreas: A population-based analysis of prognosis and survival

Background: Adenosquamous carcinoma of the pancreas is rare. Our understanding of the disease and its prognosis comes mainly from small retrospective studies. Methods: Using the Surveillance, Epidemiology, and End Results (SEER) database (1988 to 2007), we identified patients with adenosquamous carcinoma (n = 415) or adenocarcinoma (n = 45,693) of the pancreas. The demographics, tumor characteristics, resection status, and survival were compared between the groups. Results: Compared with patients with adenocarcinoma, patients with adenosquamous carcinoma were more likely to have disease located in the pancreatic body and tail (44.6% versus 53.5%, P < 0.0001). While the stage distribution was similar between the two groups, adenosquamous carcinomas were more likely to be poorly differentiated (71% versus 45%, P < 0.0001), node positive (53% versus 47%, P < 0.0001), and larger (5.7 versus 4.3 cm, P < 0.0001). For locoregional disease, resection increased over time from 26% in 1988 to 56% in 2007. The overall 2-y survival was 11% in both groups. Following resection, patients with adenosquamous carcinoma had worse 2-y survival (29% versus 36%, P < 0.0001). Resection was the strongest independent predictor of survival for patients with locoregional pancreatic adenosquamous carcinoma (HR 2.35, 95% CI = 1.47-3.76). Conclusions: This is the first population-based study to evaluate outcomes in adenosquamous carcinoma of the pancreas. Compared with pancreatic adenocarcinoma, adenosquamous carcinoma was more likely to occur in the pancreatic tail, be poorly differentiated, larger, and node positive. The long-term survival following surgical resection is significantly worse for adenosquamous cancers; however, patients with adenosquamous carcinoma can still benefit from surgical resection, which is the strongest predictor of survival.