For example, a single nucleotide polymorphism (SNP) within a let-7 target site in KRAS is associated with increased risk for non-small cell lung carcinoma [5], ovarian cancer [6] and triple negative breast cancer [7]: the variant allele enhances KRAS expression in vitro by reducing let-7-mediated suppression [5]. This evidence concerns the gene KRAS and non-small cell lung carcinoma.