Low Stromal Area and High Stromal Microvessel Density Predict Poor Prognosis in Pancreatic Cancer

Excessive stroma is a unique property of cancer tissue of the pancreas. The aim of this study was to analyze the relationship of cancer stromal area (SA) and tumor microvessel density (MVD) with prognostic and clinicopathological findings. Pancreatic adenocarcinoma tissues obtained from 104 patients were subjected to cytokeratin 19 and CD31 double immunostaining to identify cancer cells and endothelial cells simultaneously. Stromal area and MVD were assessed in the same sections. Patients were divided into 2 groups for each analysis by the median value of the respective measure. Stromal area negatively correlated with MVD. The low SA group harbored more poorly differentiated carcinoma than the high SA group. Patients of the low SA group showed a higher incidence of hematogenous recurrence. As a consequence, patients in the low SA and the high MVD groups had poorer prognosis in terms of both disease-free survival and overall survival than their respective groups. Multivariate analysis showed that a low SA was an independent prognostic factor for disease-free and overall survival. Our data indicate that the stroma of pancreatic cancer may play an auxiliary role as a barrier to cancer cell invasion. The depletion of tumor stroma alone does not suppress pancreatic cancer progression.