Association between mast cells of different phenotypes and angiogenesis in colorectal cancer

It is known that mast cells proliferate in solid tumours and increase tumour angiogenesis. Nevertheless, there is no consensus regarding their role in colorectal cancer (CRC). In this study, we aimed to clarify the relationship of mast cells positive for tryptase (MCts) and tryptase-chymase (MCtcs) with microvessel density (MVD) in the intratumoral zone and the invasive edge of 80 CRC patient tumours. We evaluated these parameters and associated their expression with clinicopathological parameters, including survival rate. Tumour sections from each patient were immunostained for tryptase to evaluate MCts, chymase to evaluate MCtcs, and CD34 to evaluate microvessel counts under x100 microscopy. The number of MCs of both phenotypes and the MVD counts were higher in the invasive edge than in the intratumoral zone (p<0.001). MCt numbers were higher than those of MCtcs in all Astler-Coller stages in both regions. A positive correlation between MVD and MCts or MCtcs was observed (Pearson's test p<0.001). Neither the number of MCs nor MVD was associated with overall survival (log rank test). However, only 8.3% of patients with low numbers of MCtcs in the invasive edge succumbed to the disease, compared to 32% with high numbers of MCtcs. Our results indicate that angiogenesis and MC hyperplasia are events which appear early during CRC development. The correlation of MC phenotypes with MVD is in agreement with the role attributed to MCs, that of angiogenesis enhancement. Collectively, these findings suggest that screening during the early malignization of CRC can provide valuable clinical information.