Russo et al. observed a high frequency of mutations in KRAS (43%), APC (17%), BRAF (4%), NRAS (4%), PIK3CA (4%), and TP53 (11%) in rectal cancer, and these mutations were well associated with a complete response to nCRT, especially in patients with BRAF, NRAS, APC, or TP53 mutations [33]. This evidence concerns the gene PIK3CA and rectal cancer.