HRAS and lip and oral cavity carcinoma: H-RAS 81 C allele has been shown to be a dominant genetic susceptibility factor for the development of many cancers in comparison to T allele; individuals harboring the homozygous and heterozygous 81C-genotype are at an increased risk of thyroid cancer, gastric cancer, colon cancer, bladder and oral cancer [14-16, 27-29].