SMAD4 and neoplasm: Additionally, significant differences were noted by tumor site for the prevalence of mutations in the following genes: KRAS, TP53, BRAF p.V600E, BCL9, AMER1, FBXW7, PIK3CA, TCF7L2, SMAD2, SMAD4, and CTNNB1. Compared with stage 1 tumors, RTK/RAS pathway mutations occurred more frequently in stage 4 (OR 1.65, 95% CI 1.34–2.05, P = 3.86 × 10− 06), and stage 2 and 3 tumors (OR 1.32, 95% CI 1.14–1.52, P = 1.56 × 10− 04) (Supplementary Table S7).