(A and B) 5hmC levels were evaluated by immunohistochemistry on a tissue microarray containing 656 patient samples from 19 different tumor types. (A) Representative pictures showing high and low levels of 5hmC from 3 different cancer types. IDC, invasive ductal carcinoma; SCC, squamous cell carcinoma. Arrowheads: 5hmC-positive stromal cells used as internal control staining. Scale bar: 100 μm. (B) Proportion of tumor samples with different amounts of 5hmC for each cancer type. Tumors were considered 5hmC-high when at least 5% of tumor cells presented signal equal to or higher than that of adjacent stroma, and 5hmC-low when fewer than 5% of tumor cells did. Negative (NEG) tumors did not show any detectable 5HmC signal in cancer cells. Diff, diffuse; int, intestinal; CRC, colorectal cancer; UCC, urothelial carcinoma; GBM, glioblastoma; SC, sebaceous carcinoma. (C and D) Histological quantification of 5hmC in paired primary tumor and liver metastases of CRC patients evaluated by immunofluorescence on formalin-fixed, paraffin-embedded sections. (C) Proportion of 5hmC-positive (green) and -negative (blue) cases (n = 197). (D) Paired comparison of primary tumors and liver metastases from synchronous nontreated patients (n = 96) from the cohort analyzed in C. P value of Wilcoxon paired test.