[Genetics-based prognosis evaluation of patients surgically treated for sporadic colorectal cancer].

The basic assumption as rationale of this research was that DNA repair genes (MMR system) are at beginning of the genetic mutational cascade causing the induction of oncogenesis of sporadic colorectal cancers as well as their multiclonal heterogeneity. In a previous study the Authors randomly selected, from a series of 256 patients, 29 patients up to the age of 60 years who underwent surgery for colorectal carcinoma with radical intent. All selected cases were considered as sporadic cancers from a clinical point of view, since none of them fulfilled the Amsterdam criteria for HNPCC and familial adenomatous polyposis was included too. Mismatch repair gene proteins expression and, in particular, gene hMSH2 protein was investigated by immunohistochemistry analysis. In 12 cases (41.4%) hMSH2 exhibited strong expression in the tumoral cells as well as in the surrounding mucosa and at distant mucosa. In 14 cases (48.3%) loss of hMSH2 protein expression was observed in tumoral cells and low immunoreactivity was detected in peritumoral mucosa while strong hMSH2 expression was observed in distant mucosa. In a third small group of patients (10.3%) loss of hMSH2 protein expression was detected in tumoral, adjacent and at distance normal mucosa. After a five years follow up, 100% of twelve patients of first group are still alive vs 64.3% of fourteen patients of second group, while in the third group only one patient survives. These results support the hypothesis of an involvement of hMSH2 gene defect in development of a subset of sporadic colorectal cancer. For the patients with strong expression of hMSH2 in the tumoral cells as well as in the surrounding mucosa and at distant mucosa, this parameter could represent an independent criterion for a good prognostic value.