Genetic variations are frequent in humans, and the challenge of cancer biology is to discover which polymorphisms influence cancer risk.Single nucleotide polymorphism (SNP) is the largest type of inherited genetic variation, of which there are at least 4.5 million.Case control studies provide valuable information in determining the degree of association between SNPs and cancer risk.Molecular investigations attempt to comprehend the mechanisms of action of these small genetic changes and how they interact with host and environmental factors leading ultimately to malignant transformation.The hope is to use genetic variations as biomarkcrs to improve prevention and treatment strategies of cancer.