Effect modification of meat intake by genetic polymorphisms on colorectal neoplasia susceptibility

Colorectal cancer incidences differ considerably between Western and non-Western countries. In recent years, a dramatic increase in colorectal cancer incidence has been reported in several Asian countries. Immigration studies have suggested that environmental rather than genetic factors are primarily responsible for the international variability and secular trends of colorectal cancer incidence rates. Therefore, not only the main effect of a gene but also the influence of gene-environment interactions on cancer risk are important from the public health perspective. This review encompasses the literature on gene-diet interactions, particularly focusing on meat intake and its association with the risk of colorectal carcinoma or adenomas. It is generally accepted that genotypes which are associated with the higher enzyme activity for metabolic activation or lower activity for detoxification would affect individual's susceptibility to meat carcinogens. The most intensively studied genes were those involved in xenobiotic metabolism, including N-acetyltransferase (NAT), cytochrome P450 (CYP) families, glutathione S-transferase (GST), and sulfotransferase (SULT). However, the associations were not consistent across studies. The role of genetic polymorphisms and their role in effect modification of environmental carcinogens should be assessed in well-designed large-scale epidemiological studies with comprehensive information for risk factors for better understanding the etiologic role of dietary factors and in developing a personalized cancer prevention strategy in the genome-wide association study era.