Analysis of gene expression patterns showed differences at the level of 93 genes, differentially expressed in young and old colorectal cancer patients [328]; this analysis also showed that the RAS, MAPK, WNT and DNA repair genes are equally expressed in both age groups, whereas PI3K-AKT signaling is more specific to early-onset colorectal cancer and cell-cycle pathways to older patients [328]. This evidence concerns the gene PIK3CA and colorectal cancer.