Fig. 5

Features of POLE-mutant CRCs. a Mean methylation score in various subgroups of CRCs categorised by POLE mutation, MSI, and MLH1 promoter methylation status. The mean methylation score in each subset was calculated based on the MLH1, MGMT, and SFRP2 gene (six loci). In the red box plot diagrams, the horizontal line within each box represents the median; the limits of each box are the interquartile ranges, the whiskers are the maximum and minimum values, and the green horizontal bar within each box depicts the mean value. The numbers under the green horizontal bar denote the mean methylation score. The P values above the square panels are statistical differences among any two individual groups calculated by the Steel–Dwass test. b Representative immunohistochemical images for the cytotoxic T-cell marker CD8 (brown) in POLE-mutant CRC samples. c Association among age at diagnosis, MLH1-AB region methylation status, and the number of CD8-positive ( +) cells per HPF in POLE-mutant CRCs. The P value is calculated by the Kruskal–Wallis test. Red circles denote patients with POLE proofreading mutations. HPF; high-power field (× 400)