LAKE TAHOE, CALIF. — The frequency of colonoscopies to screen for cancer in patients with Crohn's disease colitis or ulcerative colitis should be based on how long they've had colitis, Dr. Joshua R. Korzenik said at a meeting on gastroenterology and hepatology sponsored by the University of California, Davis.
Without that pressing motivation, a screening colonoscopy typically would be appropriate every 3–4 years during the first decade of a patient's Crohn's or ulcerative colitis. Because these patients can develop cancer not only from polyps but from flat, normal-appearing mucosa, multiple biopsies are needed. A minimum of 33 biopsies should be taken, spaced about every 4–10 cm throughout the colon. “That has about a 90% likelihood of picking up dysplasia,” said Dr. Korzenik, codirector of the Crohn's and Colitis Center at Massachusetts General Hospital, Boston.
In patients who've had Crohn's or ulcerative colitis for 10–20 years, screening colonoscopy should be performed every other year. For patients with a disease duration longer than 20 years, annual screening colonoscopy is preferred.
If the colonoscopy detects high-grade dysplasia, the patient should undergo a colectomy, Dr. Korzenik advised. Some physicians recommend colectomy for patients with low-grade dysplasia as well, “but that's still an area of dispute,” he added.