Mutations in KRAS are observed in early intraepithelial neoplasia, while TP53, Mothers against decapentaplegic homolog 4 (SMAD4), and BRCA2 DNA repair associated (BRCA2) happen at an advanced stage and invasive carcinomas [74,88,89,90,91,92] (Figure 3). The gene discussed is SMAD4; the disease is intraepithelial neoplasia.