Analysis of TNFB and TNFA NcoI RFLP in colorectal cancer

We examined the relationship between the NcoI RFLP of tumor necrosis factor beta (TNFB) and alpha (TNFA) genes and the risk of colorectal cancer. The first intron of TNFB and the -308 promoter region of TNFA NcoI RFLP were ascertained from peripheral leucocytes of 136 colorectal cancer patients and 325 healthy controls. The TNFB*1/TNFB*1 homozygote was significantly predominant in patients with colorectal cancer (18.4%) compared to control subjects (9.8%) (p < 0.01), whereas there was inverse association in TNFB*2/TNFB*2. However, the association between colorectal cancer and TNFA genotypes was not found which indicates that these alleles did not appear to be a susceptibility factor for colorectal cancer. TNFB polymorphism was not associated with a clinicopathological parameter of colorectal cancer. However, in regard to the degree of recurrence during the postoperative survival period, TNFB*1/TNFB*1 (12.5%) and TNFB*1/TNFB*2 (24%) were higher than TNFB*2/TNFB*2 (8.3%). Based on these results, it indicates that TNFB*1/TNFB*1 genotypes show an increased risk for colorectal cancer, and that the TNFB*1 allele (R.R. = 1.41) mediates some role in the initial step of tumorigenesis or activation of dormant tumor cells, whereas TNFB*2 allele mediates some functions associated with cytotoxicity of tumor cells.