Flat, nonpolypoid colorectal tumors appear to be common and may develop into cancer compared to those most routinely diagnosed type of colorectal polyps. Flat lesions are hard to find and blend with surrounding healthy tissues.
Dr. Roy M. Soetikno and associates with the Veterans Affairs Palo Alto Health Care System found that the flat and depressed type of lesions were almost 10 times more likely to be cancerous than polypoid lesions.
"Non-polypoid colorectal neoplasms are more difficult to detect by colonoscopy or computed tomography colonography because the subtle findings can be difficult to distinguish from those of normal mucosa (membrane)," the study's authors said. "As compared with surrounding normal mucosa, NP-CRNs appear to be slightly elevated, completely flat, or slightly depressed."
Colorectal cancer, also called colon cancer or large bowel cancer, includes cancerous growths in the colon, rectum and appendix. It is the third most common form of cancer and the second leading cause of cancer-related death in the Western world.
