FOXP3 and neoplasm: High-level microsatellite instability CRCs showed a trend towards a higher infiltration with FOXP3-positive cells in the tumour stroma (median: 181.5 cells per 0.25 mm2 in MSI-H vs 137.1 cells per 0.25 mm2 in MSS, P=0.06) and a significantly higher intraepithelial infiltration with FOXP3-positive Treg cells (median: 8.5 cells per 0.25 mm2 in MSI-H vs 3.1 cells per 0.25 mm2 in MSS, P<0.001).