Previous epidemiological studies declared the NAT2 rapid acetylator phenotype as a hazardous factor for cancer, especially CRC, in subjects exposed to meat and tobacco heterocyclic amines (Hein et al., 1993; Chen et al., 1998; Chan et al., 2005; Nöthlings et al., 2009; Andersen et al., 2013; Voutsinas et al., 2013), but others proposed that it was a protective factor (Hubbard et al., 1997; Heinimann et al., 1999). The gene discussed is NAT2; the disease is colorectal carcinoma.