Stage II colon cancer (CC), although diagnosed early, accounts for 16% of CC deaths. Predictors of recurrence risk could mitigate this but are currently lacking. By using a DNA methylation-based clinical screening in real-world (n = 383) and in TCGA-derived cohorts of stage II CC (n = 134), we have devised a novel 40 CpG site-based classifier that can segregate stage II CC into four previously undescribed disease sub-classes that are characterised by distinct molecular features, including activation of MYC/E2F-dependant proliferation signatures. By multivariate analyses, hypermethylation of 2 CpG sites at genes CDH17 and LRP2, respectively, was found to independently confer either significantly increased (CDH17; p-value, 0.0203) or reduced (LRP2; p-value, 0.0047) risk of CC recurrence. Functional enrichment and immune cell infiltration analyses, on RNAseq data from the TCGA cohort, revealed cases with hypermethylation at CDH17 to be enriched for KRAS, epithelial-mesenchymal transition and inflammatory functions (via IL2/STAT5), associated with infiltration by 'exhausted' T cells. By contrast, LRP2 hypermethylated cases showed enrichment for mTORC1, DNA repair pathways and activated B cell signatures. These findings will be of value for improving personalised care paths and treatment in stage II CC patients.
Keywords: LINE1; epigenetics; immune contexture; oncogene signalling; stage II colon cancer biomarkers; transforming growth factor beta (TGFβ).