Although the colonoscopy is considered the most effective means to detect precursors of colon cancer, the overall reported rate of missing colorectal tumors is 24 percent, as reported in 1997.
In the past 10 years, significant advances in screening technologies have led to the development of colonoscopes (long, flexible, lighted tubes with attached cameras) that have a wider angle of view and non-white light capabilities, such as narrow band imaging (NBI).
Researchers from the Veterans Affairs Palo Alto Medical Center in Palo Alto, Calif. utilized current technologies to study the colonoscopic polyp miss rate, comparing NBI to white light imaging.
NBI changes the white light normally emitted by the colonoscope to a bluish light, providing a narrower wavelength and enhancing visual contrast of the surface structure of the colon. In this study, two consecutive, same-day colonoscopies were performed in 276 patients. All colonoscopies used a wide angle of view (170 degrees compared to standard 140) and high resolution capabilities. The patients were randomly assigned to white light (141 patients) or NBI (135 patients) during the first withdrawal, and then immediately underwent a second examination by the same physician using white light.
The study found an overall miss rate of 12 percent for tumors of any size and three percent for tumors greater than or equal to six millimeters. No lesion larger than one centimeter was missed and all missed tumors were tubular adenomas, or non-cancerous tumors. Based on these results, researchers established the colorectal tumor miss rate as zero percent (up to 2%) for significant tumors and 12 percent for all tumors. However, no significant difference of missed lesions was found between NBI and white light.
“Our findings suggest that technological advances have led to a significant reduction in the overall colorectal tumor miss rate, establishing a new benchmark for more accurate screening and detection,” said Roy Soetikno, M.D., of Stanford University in Stanford, Calif., and senior author of the study. “Our study reaffirms the role of colonoscopy as the gold standard method to screen for colorectal cancer.”