Somatic mutations in both TP53 and KRAS are the most frequent oncogenic alterations in human cancers, and defects in their function cause tumor development and growth in various types of cancers.20,21 In this study, the frequency of TP53 and KRAS mutations was comparable between advanced anal and rectal AD, suggesting that both are mainly involved in the oncogenesis of both. The gene discussed is KRAS; the disease is cancer.