Association between colorectal cancer and red or processed meat among Korean diet: A molecular approach

Abstract

To study whether red or processed meat cause colorectal cancer in non- western population, we performed a pilot study in Korean people (N=30, case, 15 vs. control 15, mean of age=59.7 yrs) with biological monitoring of exposure and response biomarkers, i.e. metabolites of polycyclic aromatic hydrocarbons and heterocyclic amine (1-OHP, PhIP, and MeIQx), their DNA-adducts (dG-C8-MeIQx), and homocysteine, malondialdehyde (MDA), C-reactive protein and epigenetic alteration (5mC). The subjects also filled out daily consumption of food before diagnoses. As results, they averagely consumed 59.89 g/day and 2.47 g/day of red and processed meat, respectively. There were positive associations among consumption of Kimch(g), folate (ug) and fruits(g). The consumption of red meat was not associated with the cancer and the control even showed higher processed meat (g). From biomonitoring, the average levels of urinary 1-OHP, PhIP, and MeIQx, blood-dG-C8-MeIQx and 5mC were 0.13 ppb, 9.9 ppt, 14.63 ppt, 5.23 ppt/1.8 ug of DNA, and 5.3%, respectively. We found younger people more consumed processed meat or beverage and showed higher urinary levels of MeIQx than elderly people. The urinary levels of PhIP were negatively associated with folate consumption. The cases showed higher levels of LDL-cholesterol, homocysteine, urinary 1-OHP and dG-C8-MeIQx than controls. There were positive associations among levels of MeIQx, MDA, and 1-OHP. In addition, levels of dG-C8-MeIQx were positively associated with those of 1-OHP and total cholesterol. The levels of global methylation of 5mC (%) were higher in well done meat consumers than others. In conclusion, the Korean subjects might consume less volume of red or processed meat than western people. From questionnaire (FFQ), we could not find association between red or processed meat and colorectal cancer. However, biological monitoring showed the Korean colorectal cancer could be affected by red or processed meat, due to association with exposure or response biomarkers, particularly long term exposure biomarkers, such as dG-C8-MeIQx. This molecular epidemiological approach provides more reliable evidences to overcome limitation of case-control studies.