Prognostic significance of mast cell number and microvascular density for the survival of patients with primary colorectal cancer

Background and Aim: The prognostic relevance of tumor-related angiogenesis and mast cell presence in colorectal cancer remains controversial. The aim of the current study was to assess the mast cell and microvessel densities (MCD and MVD) in the invasive front of colorectal cancers and to determine their prognostic relevance for survival of the patient with colorectal carcinoma. Methods: Histochemistry and immunohistochemistry were used to identify mast cells by toluidine blue (TB) histochemical staining and tryptase (Try) immunohistochemical staining and to determine the MVD in 106 biopsies from patients with 57 colonic and 49 rectal primary cancers. The MVD was assessed using CD31 as an endothelial cell marker. Results: Significant positive correlations were found between the MVD in the 'hot spots' and MCD-Try and MCD-TB (R = 0.623 and R = 0.414, respectively, P < 0.001). The survival analyses showed that the patients with hypovascular tumor tissues had significantly longer survival than those with hypervascular tumor biopsies (P < 0.0001). Analogous significant correlation was observed for MCD-Try: patients with low MCD-Try had significantly better prognosis compared to those with high MCD (P = 0.038). In the multivariate Cox's hazard analysis of the 'hot spots' MVD was found to be an independent prognostic factor (P = 0.0007), together with the presence of invasion of lymph vessels (P = 0.017) and the presence of regional lymph node metastases (P = 0.028). Conclusion: We suggest that the assessment of MVD and tryptase-positive mast cells in the invasive front of the primary colorectal cancer could be a useful tool for prognosis of patients after surgical therapy.