Osteopontin Expression is Associated with Improved Survival in Patients with Pancreatic Adenocarcinoma

Osteopontin (OPN) is a secreted protein of the extracellular matrix. It has been used as a marker for tumor aggressiveness and correlated with clinical outcomes in several solid tumors, such as liver, lung, and breast. We determined the OPN expression and its influence on survival in patients with resected pancreatic adenocarcinoma. Tissue microarrays were constructed from 245 resected pancreatic adenocarcinomas. Immunohistochemical staining for OPN was undertaken and compared to normal pancreas (n = 12). OPN expression was then correlated with patient demographics, tumor size, grade, node, and margin status. Survival curves were created by the Kaplan-Meier method and compared by log rank analysis. In total, 181 (74 %) of pancreatic adenocarcinoma tissues expressed OPN compared to 7 (58 %) of normal controls (p = 0.004). Expression was observed predominantly in the cytoplasm of the tumor cells. The median and 2 year overall survival was longer when OPN was expressed (17.1 vs. 11.6 months, and 38 vs. 24 %, respectively, p = 0.04). Multivariate analysis showed OPN expression and T stage to be independent predictors of overall survival, while other histopathologic factors such as tumor grade, tumor size, and nodal status were not. These results suggest that the presence of OPN expression in pancreatic adenocarcinoma may have a protective effect independent of tumor stage. This emphasizes the importance of the interaction between pancreatic cancer cells and their stromal elements.