Highly proliferative intratumoral fibroblasts and a high proliferative microvessel index are significant predictors of tumor metastasis in T3 ulcerative-type colorectal cancer.

Fibroblast and endothelial cell mitotic figures are seen in some areas of colorectal cancers, and the purpose of this study was to investigate whether the proliferative activity of fibroblasts and endothelial cells plays an important role in tumor progression of T3 ulcerative-type colorectal cancer. The tumor area of 157 colorectal cancers was divided into marginal elevated area and central depressed area (CDA), and at half the depth of the depression the CDA was in turn divided into CDA upper area (CDAU) and CDA lower area (CDAL). The proliferative activity of the tumor cells, fibroblasts, and endothelial cells was assessed immunohistochemically by double CD31/MIB-1 (anti--Ki-67 antigen) staining. The proliferative microvessel index was estimated as the percentage of microvessels lined by MIB-1-positive endothelial cells relative to the total microvessel count. Proliferative activities of tumor cells showed significant associations with those of fibroblasts and the proliferative microvessel indices in all of the corresponding areas. Proliferative activities of fibroblasts also showed significant associations with proliferative microvessel indices in all of the corresponding areas. Colorectal cancers with nodal metastasis showed significantly higher proliferative activities of fibroblasts in the CDAU than those without nodal metastasis (P <.001). The high proliferative activities of fibroblasts and proliferative microvessel indices in the CDAU showed significant associations with short distant organ metastasis-free periods in colorectal cancers without nodal metastasis (P <.001 and P =.010, respectively) and those with nodal metastasis (P =.024 and P =.036, respectively). Multivariate analysis showed that the highly proliferative fibroblasts in the CDAU significantly increased hazard rates of distant organ metastasis of colorectal cancer patients with nodal metastasis (P =.018). Proliferative activities of fibroblasts and endothelial cells in the CDAU are useful parameters for predicting tumor metastasis in patients with T3 ulcerative-type colorectal cancer. HUM PATHOL 32:401-409. Copyright 2001 by W.B. Saunders Company