WebMD features comments by Leonard Augenlicht, Ph.D., expressing concern over new research on a simple blood test that some researchers say has the potential to detect the majority of colon cancers. Dr. Augenlicht notes that the only definitive early screening test for colon cancer is the colonoscopy and the new noninvasive blood test, which may not be valid, could discourage patients from proper testing. Dr. Augenlicht is professor of medicine and cell biology.