The role of SPARC expression in pancreatic cancer progression and patient survival

Background. Secreted protein acidic and rich in cysteine (SPARC) is a matricellular glycoprotein that has been implicated in tumor-stroma interactions in pancreatic cancer. Here we evaluated the expression of SPARC during the progression of pancreatic cancer and its correlation with survival following curative intent surgery. Methods. The expression profile of SPARC was investigated in normal pancreas, invasive adenocarcinoma, and lymph node metastasis by immunohistochemistry. Kaplan-Meier and multivariate Cox regression were used to assess for mortality risk. Results. None (0%) of 10 normal pancreata, 68 (77%) of 88 primary tumors, and 28 (67%) of 42 lymph node metastases were labeled with the SPARC antibody used in this study. SPARC was expressed exclusively in stromal cells. The survival of patients with high stromal SPARC expression was significantly worse than that of the patients with low stromal SPARC expression (11.5 vs 25.3 months; p = 0.020). Multivariate analysis showed that stromal SPARC expression (hazard ratio (HR) 2.12; p = 0.012), tumor location (body/tail) (HR 2.95; p = 0.003), and adjuvant chemotherapy (HR 0.55; p = 0.018) were significant independent risk factors. Conclusion. This study describes the pattern of SPARC expression in pancreatic neoplastic progression and supports the role of stromal SPARC expression as a prognostic factor and target for directed therapy.