TP53 and colorectal cancer: It may however be noted that studies which examined the gene-gene or gene environment interactions, the protective effect of the p53 Arg72Pro variant allele was seen in combination with other genotypes like the p53 intron 6 diplotype for head and neck cancers [42] and gastric cancer [41] or with the use of non steroidal anti-inflammatory drugs in colorectal cancer [44].