This pilot study aimed to assess an original test based on the analysis of exfoliated colonocytes as a new approach to colorectal cancer (CRC) detection. DNA was isolated from exfoliated cells collected from the surface of the rectal mucosa by a standardized minimally invasive procedure in a case-control trial involving 66 patients with CRC diagnosis and 110 healthy volunteers (age 50-70). PicoGreen staining and quantitative real-time PCR (QRTPCR) were used for DNA quantification. Mean DNA scores in lg/ml obtained for the control and cancer groups were 2.1 (95% CI 1.7-2.5) and 9.0 (CI 6.7-11.2) respectively (p < 0.001) for PicoGreen and 0.8 (CI 0.6-0.9) and 3.8 (CI 1.9-5.7) respectively (p 5 0.003) for QRTPCR. The PicoGreen assay better detected CRC presence. At DNA score cut-off point of 2.5 lg/ml this assay gave sensitivities of 77.8% ) for proximal tumours, 91.4% (CI 76.9-98.2) for distal CRC and 86.8% ) for all CRC with specificity at 74.0% (CI 64.0-82.4). Increasing the cut-off point to 5.0 lg/ml resulted in sensitivities of 38.9% 3) for proximal tumours, 71.4% (CI 53.7-85.4) for distal CRC and 60.4% (CI 46.0-73.5) for all CRC. Specificity for this cut-off point increased to 94.8% 3). The new procedure of exfoliated cell collection from the surface of the rectal mucosa is a simple, safe and well-tolerated technique providing high quality cells. These early results suggest that exfoliated cell collection in combination with DNA quantification can potentially be employed as a tool for CRC early detection.Colorectal cancer (CRC) is one of the most common fatal malignancies. 1 CRC mortality can be greatly reduced by early tumour detection through population screening, 2-6 but the choice of CRC screening methods is still limited with two main categories: i) stool tests comprising different versions of faecal occult blood test (FOBT) and molecular analysis of stool DNA; ii) structural examinations including full colonoscopy, flexible sigmoidoscopy, double contrast barium enema and computed tomographic colonography. 6 Although the validity of the structural exams, especially colonoscopy, is well proven, they are either highly invasive or technically complex and expensive. 3,7 In many countries FOBT remains the most popular mass screening method due to its low cost, noninvasiveness and simplicity, however this test often produces both false-negative and false-positive results. [3][4][5][6][8][9][10] Stool DNA analysis targeting molecular markers in exfoliated colonocytes excreted with faeces is being actively developed, 12-18 but its suitability for CRC screening is still questioned. Purification of human DNA from stool is difficult, [14][15][16] and there is no unique molecular signature reliably indicating cancer presence. The latter difficulty resulted in the use of multimarker assays, 3,9,[11][12][13][14][15][16][17][18] making the cost-effectiveness of the approach a major issue. 9,[19][20][21] It has been suggested that exfoliated colonocytes collected directly from the surface of colonic mucosa could serve f...