Correlation of ESR1 methylation and protein score staining in the immunohistochemical analysis. The statistical data showed the correlation between intensity of ERα staining by IHC and frequency of ESR1 promoter methylation. The dark bars denote methylated samples and grey bars unmethylated samples. The samples with ERα expression (score 0 to 3, see material and methods) that showed methylation were: scored 0 - 25 with 15 methylated (60%); score 1 - 22 with 8 methylated (36%); score 2 - 16 with 5 methylated (31%), score 3 - 6 samples without methylation. These results show the percentage of samples that were significant with p < 0.0001.