A fast-track research letter in this weeks issue of THE LANCET describes how the detection of a specific mutation in faecal DNA could be a reliable method for identifying a subset of proximal colorectal cancers. If successful, the new assessment, when combined with sigmoidoscopy or other DNA-based tests, could be advantageous over more difficult and expensive techniques such as colonoscopy.
The assessment of mutations in faecal DNA offers promise for non-invasive colorectal cancer diagnosis; most previous studies have focused on the more common lesions of the distal colon and rectum. The new study, by Giovanni Traverso, Kenneth Kinzler, and Bert Vogelstein from Hopkins Kimmel Cancer Center, Baltimore, USA, and colleagues focused on patients with proximal cancers-tumours that should be the most difficult to detect as they are furthest from the anus.
The investigators analysed 134 stool samples, which included 46 patients with known cancers in the proximal colon. Faecal DNA analysis revealed that 17 of the 134 patients had alterations to the BAT26 gene, a genetic marker for colorectal cancers. Each of these 17 samples was derived from a patient with cancer, and no false positive results were observed in patients without cancer. Subsequent analysis revealed that 18 of the 46 studied cancers harbored BAT26 alterations in their tumours, and that 17 of these 18 (94%) were identifiable by faecal DNA assessment.
Bert Vogelstein comments: These results have several important implications for faecal DNA testing. They provide compelling evidence that mutations in stool can be used to identify patients with proximal cancers. The high specificity of the analysis, with zero false positives, was very encouraging. We hope that this approach will provide an important addition to the options
Contact: Richard Lane