Among new approaches to colorectal cancer screening that are being explored are ways to improve visualization of the colon. One technique is capsule colonoscopy (also called capsule endoscopy), in which a person swallows a pill-like capsule that contains a tiny wireless camera. The camera takes pictures of the inside of the digestive tract and sends them to a small recorder that is worn on the patient’s waist or shoulder. The pictures are then viewed on a computer by the doctor to check for signs of disease. The capsule passes out of the body during a bowel movement. Cleansing of the colon is still necessary before this test. This method is currently approved for patients with an incomplete colonoscopy and for detection of colon polyps in patients with evidence of lower GI bleeding but not as a stand-alone screening test.
One new approach to colorectal cancer screening is to look for cells released by colorectal polyps and tumors into the bloodstream (24). These so-called circulating tumor cells (CTCs) are rare, however. Researchers have developed an ultrasensitive antibody-linked CTC detection technology to capture colorectal epithelial cells associated with colorectal tumors and adenomas in blood samples (25). In a proof-of-concept study, this blood-based CTC test was able to distinguish between patients with colorectal adenomas or cancer and people without cancer (26).
Researchers have also identified small molecules, called metabolites, in urine that may signal the presence of colorectal polyps and tumors (27, 28). In a clinical study, a metabolomic-based urine test was better able to identify patients with adenomas than stool-based tests (29).
Researchers are also trying to improve the sensitivity of stool-based screening for detecting advanced adenomatous polyps, which can potentially become colorectal cancer, by testing for the presence of multiple biomarkers. For example, measuring three protein biomarkers in stool—hemoglobin, calprotectin, and serpin family F member 2—improved the ability of FIT to detect advanced lesions (including colorectal cancer) by 35% without reducing its specificity (30).
Information about ongoing clinical trials that are studying methods for colorectal cancer screening can be found in NCI’s clinical trials database. You may also contact NCI’s Cancer Information Service at 1-800-4-CANCER (1-800-422-6237) for assistance with searching the clinical trials database.