Somatic mutation screenings: identification of individuals harbouring KRAS mutations with the use of plasma DNA

Background: Many cancers are attributed to somatic muta-tion of DNA. We investigated whether it is feasible to detect cancer-associated somatic mutations in patients with neo-plasms by using plasma DNA. Methods: Plasma samples were prospectively collected from 240 patients undergoing colonoscopy. Colorectal biopsies were performed as clini-cally indicated in 135 patients, and risk factor information was available from 232 patients. DNA was extracted from plasma and colorectal tissue and was amplified by use of a polymerase chain reaction method that enriches for muta-tions in codon 12 of the K-ras oncogene. Molecular, histo-logic, and clinical data were compared by use of two-sided Fisher’s exact test. Results: Mutations in the K-ras gene de-tected in the plasma of 64 (28%) of 232 patients were statis-tically significantly associated with colorectal cancer ris