Newer screening modalities for colorectal cancer (CRC), such as virtual colonoscopy and stool DNA assays, are currently being developed and tested. Virtual colonoscopy, which uses high-resolution computed tomographic scanning to image the colon, has been evaluated in at least two multi-center trials in the United States, with varying results.[1,2] One of the studies reported a sensitivity and a specificity of 89% and 80%, respectively, for polyps larger than 6 mm and sensitivity and specificity up to 94% and 96%, respectively, for polyps larger than 10 mm.[1] The sensitivities were equivalent to those of optical

colonoscopy in this group of asymptomatic average-risk patients.  The second study, however, found that virtual colonoscopy had a sensitivity of only 39% for lesions larger than 6 mm and 55% for lesions larger than 10 mm.[2] Given these divergent findings, it appears that there are issues related to equipment, software, and training that remain to be addressed before virtual colonoscopy can be recommended as a routine screening modality. Another consideration is that patients with lesions detected by means of virtual colonoscopy must still undergo optical colonoscopy for treatment or tissue diagnosis. Fecal DNA assays have been developed to test for mutations in multiple genes known to be involved in colorectal neoplasia and are currently being evaluated in clinical trials.[3] These modalities are not as sensitive as colonoscopy but may be useful in patients who are unable or unwilling to comply with endoscopic screening.[4]