PIK3CA and cancer: According to the Cancer Genome Atlas Network (TCGA), tobacco-dependent cancers demonstrate abnormalities in four groups of genes, viz., those regulating the cell cycle (CDKN2A and CCND1), those determining cell proliferation and survival (TP53, HRAS, PIK3CA, and EGFR), those controlling cell differentiation (NOTCH1), and a gene regulating the Wnt signalling pathway [3].