Novel genetic and epigenetic alterations in ... - Ous-research.no

tumors it is hard to establish which of the mutated genes are playing a part in tumorigenesis.A scheme of dividing the genes into driver and by-stander genes based on mutationfrequency has been suggested, and genes with mutation frequencies below 12% areconsidered to have no functional consequence on tumor development and be termed bystandergenes.[8]CRC is one of the most common cancer types and has a relatively poor 5-year survival of~60% (SEER Cancer Statistics Review, 1975-2005 * ). The most important factor for survivalis tumor stage at the time of diagnosis, i.e. depth of tumor infiltration in the bowel wall,spread to lymphatic nodes and distant spread. It has been shown that MSI tumors have abetter prognosis than microsatellite stable (MSS) tumors.[9] Still, a subset of patients withMSI-tumors have unfavorable prognosis, and identification of these patients might give theoption of improved treatment.In order to identify markers with prognostic value we have analyzed 41 genes, selected froma literature survey,[10] in two different colorectal tumor series (in total 202 samples).MATERIAL AND METHODSHypothesis generating test series94 sporadic, fresh frozen, colorectal carcinomas from Scandinavian hospitals had previouslybeen selected, being classified as MSI. The Norwegian series of 42 samples was from an* http://seer.cancer.gov/statfacts/html/colorect.html4