Adenosquamous Versus Adenocarcinoma of the Pancreas: A Population-Based Outcomes Analysis

Background: Pancreatic adenosquamous carcinoma has historically been characterized as having a more aggressive clinical course than ductal adenocarcinoma. The natural history of this disease, however, is essentially unknown. Methods: We evaluated the clinical characteristics of all patients with pancreatic adenosquamous carcinoma recorded in the California Cancer Registry 2000-2007 and compared them to those of patients with ductal adenocarcinoma. Results: Ninety-five patients with pancreatic adenosquamous carcinoma and 14,746 patients with ductal adenocarcinoma were identified. Demographics were similar between subtypes (p > 0.05). Disease stage at presentation was also similar; over 50% of each diagnostic group presented with metastatic disease (p = 0.62). Surgical resection was more common among patients with locoregional adenosquamous carcinoma than adenocarcinoma (p = 0.0004), but rates of adjuvant therapy administration were similar (p > 0.05). The cohorts' median overall survival durations were similar in a Cox proportional hazards model (p = 0.45); overall survival was also similar when only patients with resected disease were considered (p = 0.65). Early stage, resection and receipt of radiation or chemotherapy were favorable independent prognostic factors among patients with adenosquamous carcinoma. The median overall survival duration of patients with resected adenosquamous carcinoma was 12 months (95% CI, 8-52). Conclusions: Adenosquamous carcinoma has a natural history similar to that of ductal adenocarcinoma when treated with prevalent clinical patterns of care.