It is now widely accepted that sporadic colorectal cancers frequently arise from pre-neoplastic lesions through the activation of oncogenes (K-ras, BRAF) and the inactivation of tumor suppressor genes (APC, p53, DCC) and mismatch repair (MMR) genes (MLH1 and MSH2) [16,17]. This evidence concerns the gene MLH1 and colorectal cancer.