Study shows need for thorough polyp removal, continued surveillance
January 7th, 2010 by Jennifer Walker-Journey
A new study by researchers from the University of Pittsburgh School of Medicine and Epidemiology confirms the need for continued colonoscopy surveillance in patients at risk for colorectal cancer, especially those with a history of precancerous polyps. It also highlights the importance for polyps, especially those that are precancerous, to be completely removed since cancer may develop at the site of polyp removal if residual tissue remains.
The study focused on the rate of interval colorectal cancer in patients participating in the Polyp Prevention Trial Continued Follow-up Study, a four-year multicenter, randomized, controlled trial designed to examine the effects of a low-fat, high-fiber, high-fruit and vegetable diet on the recurrence of colorectal adenomas, or precancerous polyps. The University of Pittsburg study on the occurrence of interval colorectal cancer appears in the January issue of GIE: Gastrointestinal Endoscopy, the monthly scientific journal of the American Society for Gastrointestinal Endoscopy.
“Despite regular colonoscopy, interval colorectal cancer may occur,” says study lead author Robert E. Schoen. “We set out to examine the rate at which these interval cancers appear.”
The study found that nine cases of colorectal cancer were diagnosed over 7,626 person-years of observation, or a rate of 1.2 per 1,000 person-years of observation. In patients involved in the study who developed colorectal cancer, 78 percent had a history of precancerous polyps. The majority – about 78 percent – were detected at an early stage and thus were considered highly curable.
Colonoscopies are the “gold standard” for detection of colorectal cancer. Screenings are recommended for all individuals beginning at age 50 or earlier for people with a history of colorectal cancer or who are exhibiting symptoms such as blood in the stool. During colonoscopy exams, doctors can detect and remove polyps, some of which can become cancerous if not removed.