This variant, the let-7 complementary site (LCS6) in the KRAS 3′ UTR, is associated with KRAS gene upregulation and let-7 lower levels [101]; although this polymorphism correlates with a modest increase in lung cancer risk [101], other studies did not find an association between the LCS6 polymorphism and lung cancer survival, limiting its clinical usefulness in predicting an increased risk for NSCLC [102]. This evidence concerns the gene KRAS and lung cancer.