A large German, statewide cross-sectional study of colonoscopy found the prevalence of advanced colorectal neoplasms strongly reduced by 67% in left-sided lesions, but this protection did not extend when the lesions were right-sided [6]. A later study by the same authors, which emphasized high-quality

colonoscopy, found the procedure to be associated with a reduced risk of 56% for right colonic lesions, which is an improvement over earlier reports, but is less than the 84% reduced risk for CRC the authors observed for selleck chemicals left colonic lesions [7]. A number of suggestions have been advanced to explain why colonoscopy may be less effective in the right colon than in the left. The technology is operator-dependent and requires complete endoscopic evaluation, LB-100 molecular weight which is more difficult to complete in the right side of the colon. Bowel cleansing and preparation for colonoscopy may be less adequate on the right side, making lesions more difficult to visualize. Nonpolypoid flat or depressed lesions are more prevalent in the right than in the left side of the colon, and these are more challenging to identify and remove [8]. There may also be differences in biology between proximal and distal lesions; for example, distal and proximal CRCs show

genetic and molecular differences [9]. We previously reported a seven-gene, blood-based biomarker panel Tau-protein kinase for CRC detection [10]. For this current study, we hypothesize that this gene panel, which is a blood-based test, not dependent on localization, preparation or operator technique, can provide a non-biased method for detecting CRC arising in either the right or the left side of the colon. The test is intended as a pre-screening tool and convenient companion diagnostic test to help those patients who are averse to colonoscopy and to the fecal occult blood test to make an informed decision based on their individual molecular profile. Because of

its narrow focus, the test is not expected to alter clinical practice for patients who comply with recommended screening schedules. selleck Methods Sample collection procedures and details of methodology for identification of the seven-gene blood-based biomarker panel for CRC were reported in our earlier study [10]. Briefly, 9,199 blood samples were taken from screening colonoscopy subjects at twenty-four centers located in the Greater Toronto Area and surrounding regions and in the United States, between March 2005 and March 2008. Uniformity of collection procedures at the different sites was ensured by the use of identical study protocols, uniform training of personnel, and periodic site monitoring. Informed consent was obtained according to protocols approved by the Research Ethics Board of each of the participating twenty-four clinics and hospitals.