Background The need for adjuvant chemotherapy after resection of ampullary cancer (PapCa) remains undefined. Recent data suggest that a different epithelial origin of PapCa might be associated with ...different tumor biology. The aim of the present study was to assess the clinical value of morphologic and immunohistochemic subclassification of PapCa into intestinal-type (IT) and pancreaticobiliary-type (PT) to predict chemotherapy response and overall survival (OS). Methods Via a prospective database, 112 PapCa were identified, of which 95 could be included in the present study. Those were compared with 206 matching patients with periampullary pancreatic cancer (ie, pancreatic ductal adenocarcinoma, PDAC). IT and PT PapCa were classified morphologically, and tissue microarray was prepared with immunohistochemistry for CK7, CK20, MUC2, CDX2, ß-Catenin, and Villin. Multivariate survival analysis was performed. Results OS of PT patients was less compared with IT patients (25 vs 98 months; P < .001), whereas it was comparable with patients with PDAC (25 vs 14 months; P = .123). PT patients receiving adjuvant gemcitabine chemotherapy featured improved OS (32 vs 13 months; P = .013), whereas gemcitabine tended to be associated with decreased OS in IT patients (35 vs 112 months; P = .193). Besides histopathologic classification, expression of CK7 and MUC2 were important prognostic variables. PT patients with CK7-positivity or MUC2-negativity were segregated into an even poorer prognostic group. Conclusion PapCa is not a separate tumor entity. We demonstrate important differences between IT-PapCa and PT-PapCa not only in long-term survival but also in response to adjuvant gemcitabine. Tumor biology and clinical course of PT tumors resemble those of PDAC. PT tumors should therefore be treated like PDAC.
