Despite the fact that immunosuppression [39] is a risk factor for cancer development, MOR-related signaling was also independently linked with the activation of the pro-oncogenic signaling pathway involved in CRC formation; the PI3/Akt/mTOR (mammalian target of rapamycin) and Src (from ‘sarcoma’) pathways [39]. This evidence concerns the gene OPRM1 and colorectal carcinoma.