In the present study, we also observed that the combined effect of the NFκB1 and NFκBIA polymorphisms on risk of CRC was more pronounced among younger than 60 years, women, never drinkers, never smokers, persons with a normal BMI and those with a family history of cancer, suggesting that, in these subpopulations, gene-environment interaction may be very weak and the combined effect was an independent risk factor for these subpopulations. This evidence concerns the gene NFKB1 and colorectal carcinoma.