A case-control study of colorectal cancer detection by quantification of DNA isolated from directly collected exfoliated colonocytes.

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 microg/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 = 0.003) for QRTPCR. The PicoGreen assay better detected CRC presence. At DNA score cut-off point of 2.5 microg/ml this assay gave sensitivities of 77.8% (CI 52.4-93.6) for proximal tumours, 91.4% (CI 76.9-98.2) for distal CRC and 86.8% (CI 74.7-94.5) for all CRC with specificity at 74.0% (CI 64.0-82.4). Increasing the cut-off point to 5.0 microg/ml resulted in sensitivities of 38.9% (CI 17.3-64.3) 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% (CI 88.3-98.3). 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 detection by measuring DNA from exfoliated colonocytes obtained by direct contact with rectal mucosa.

The purpose of the study was to explore the potential of direct exfoliated colonocyte collection from human rectal mucosa for colorectal cancer screening. A special device was designed for standardized collection of exfoliated cells from the surface of human rectal mucosa. Material was collected from 120 outpatients selected for colonoscopy and 36 patients with confirmed diagnosis of colorectal cancer or large polyps. Determination of total DNA amounts in the collected samples (DNA scores) by PicoGreen assay and real-time PCR was employed alongside cytological assessment. Well preserved cells with cytological patterns characteristic for different colorectal conditions (cancer, inflammatory bowel disease) were detected in the collected material. In the outpatient group DNA scores were higher in patients with cancer and inflammatory bowel disease compared to those with no abnormalities detected, diverticular disease and small polyps (P<0.001 for PicoGreen assay; P=0.002 for real-time PCR). The sensitivity and specificity of the quantitative DNA test (PicoGreen assay; cut-off point 3.0 microg/ml) for detecting serious colorectal conditions were 1.00 and 0.74, respectively. In the group with confirmed tumours, the PicoGreen assay performed better for distal colorectal cancer (sensitivity 0.83; specificity 0.76) compared with proximal colon malignancies (sensitivity 0.57; specificity 0.76). It can be concluded that the proposed technique of direct collection of exfoliated cells from the surface of human rectal mucosa provides abundant cellular material suitable for diagnostic and research applications. Further refinement of the quantitative DNA test may lead to a new approach for colorectal cancer early detection and screening.