Prognosis of adenosquamous carcinoma of the pancreas: A matched case-control study.

Abstract

e14540 Background: Adenosquamous carcinoma of the pancreas (ASC), which accounts for only 1-4% of exocrine pancreatic malignancies, is a variant of pancreatic ductal adenocarcinoma (PDAC). However, the prognosis of ASC is still unclear because these reports were based on only case studies and small surgical series with early stage cancers. The purpose of the present study was to clarify the prognosis of ASC using a matched case-control study. Methods: Pathological and clinical records of ASC cases between 2001 and 2011 in our institution were examined. All ASC cases were diagnosed pathologically by a surgical or endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) specimen. First, to examine the efficacy of EUS-FNA for the diagnosis of ASC, the pathological findings of EUS-FNA were compared with the surgical findings in the resected cases of ASC. Next, to clarify the prognosis of ASC, the clinical characteristics of ASC were evaluated. As a control group, PDAC cases matched with ASC cases by sex, age, pretreatment ECOG-PS, location, initial therapy, and the AJCC TNM staging for pancreatic cancer were also included in this study. Results: Of the 914 cases of pancreatic neoplasms, 28 cases of ASC were identified (3.06%), and 56 cases of PDAC were matched as controls. Of 28 cases of ASC, 6 cases underwent curative resection, and 22 cases were unresectable. Of the 6 resected cases of ASC, 5 cases were diagnosed preoperatively by EUS-FNA (κ, 0.83; positive predictive value [PPV], 100%). Overall survival (OS) was significantly worse for ASC than for PDAC, with a hazard ratio (HR) of 1.94 (95% CI, 1.07 to 3.51; p=0.026; median 8.38 months vs. 15.75 months). Of the 22 unresected cases, the OS of ASC was significantly worse than that of PDAC, with an HR of 2.39 (95% CI, 1.27 to 4.51; p=0.007; median 4.67 months vs. 12.36 months). Conclusions: In the present study, EUS-FNA had a high PPV for the diagnosis of ASC, and ASC was found to be more aggressive than PDAC.