Small Polyps Found in Virtual Colonoscopy Rarely Malignant
0.4 percent of 6- to 9-mm polyps detected by CTC in study had high-grade dysplasia; none malignant
THURSDAY, July 1 (HealthDay News) -- Small polyps discovered in computed tomography colonography (CTC) rarely contain high-grade dysplasia or are malignant, and the malignancy rate for large polyps discovered in CTC is less than 1 percent, suggesting that less aggressive management of lesions detected by CTC may be warranted, according to research published in Clinical Gastroenterology and Hepatology.
Perry J. Pickhardt, M.D., of the University of Wisconsin in Madison, and colleagues reviewed results from 5,124 consecutive CTCs over 52 months. Non-diminutive polyps confirmed by follow-up colonoscopy were grouped by size and histological features, and rates for malignancies and high-grade dysplasia were calculated. Adenomas that were 10 mm or greater in size and/or contained high-grade dysplasia or a pronounced villous component were classified as advanced.
Overall, the researchers identified 755 polyps 6 mm or greater in size in 479 individuals during colonoscopy. The rates of malignancy were: 0 percent for 464 polyps 6 to 9 mm in size; 0.9 percent for 216 polyps 10 to 19 mm in size; 6.1 percent for 33 polyps 20 to 29 mm in size, and 38.1 percent for 42 polyps 30 mm or greater in size. High-grade dysplasia was found in 0.4 percent of the polyps 6 to 9 mm in size and 7.9 percent of the polyps 10 mm or greater, and a prominent villous component was observed in 3.4 percent of the polyps 6 to 9 mm in size. The rate of advanced histology was 3.9 percent in 6- to 9-mm polyps.
"Because CTC is a non-therapeutic test, these results have important implications for the management of CTC-detected lesions of this size. Because there is a need to balance the risk of existing or future cancer development against the risks and costs related to colonoscopy referral for polypectomy, a less-aggressive management strategy may be prudent for smaller polyps," the authors write.
Two study authors are consultants for Viatronix and Medicsight, and are co-founders of VirtuoCTC.