Association of prion protein expression with pancreatic adenocarcinoma survival in the SEER residual tissue repository

Pancreatic ductal adenocarcinoma (PDAC) is an important cause of cancer death with no clear prognostic biomarker. Expression of prion (PrP) has been reported to be a marker of poor prognosis in a series of Caucasian PDAC cases. We determined the prognostic value of PrP in a racially and geographically diverse population-based series of PDAC cases. PrP expression was examined in 142 PDAC cases from three cancer registries. Cases included 71 Caucasian, 54 Asian/Pacific Islanders and 17 Blacks diagnosed from 1983-2000, and followed through 2008. Hazard ratios (HR) and 95% confidence intervals (CIs) for the association of PrP expression with survival were computed after adjustment for case attributes. The risk of death was about four times higher (HR=3.8; 95% PDAC cases with PrP⁺ tumors (median survival 5 months) compared to the 34 cases with PrP^- tumors (median survival 20 months). Of 51 cases with resected, localized PDAC median survival was 74 months for 17 cases with PrP^- tumors versus 14 months for 34 cases with PrP⁺ tumors (HR=6.7; 95% CI: 2.6, 17.4). All 6 surviving cases had PrP^- negative tumors (median survival, > 10 years). PrP may have potential as a prognostic biomarker in PDAC patient management.