Five years after a colonoscopy found and removed polyps, one in ten patients will have a new advanced polyp and six in every thousand will be diagnosed with colorectal cancer.
Pooling studies that followed up nearly 10,000 men and women who had a polyp removed during a colonoscopy (polypectomy), researchers found 1,082 with a later advanced adenoma and 58 with colorectal cancer. Median follow-up time was 47 months.Risk for advanced adenomas or cancer were greatest for those who had five or more polyps removed originally. One in four (24.1 percent) would have either a large polyp or cancer within five years. One in five (19.3 percent) w0uld have advanced lesions when the original polyp was more than 2 centimeters (a little less than an inch).
Men were at higher risk as were older people. Risk was also increased when the original polyp was found in the right side of the colon, and when it had villous features.
Maria Elena Martinez and her colleagues concluded,
Occurrence of advanced colorectal neoplasia is common after polypectomy. Factors that are associated most strongly with risk of advanced neoplasia are patient age and the number and size of prior adenomas.
SOURCE: Martinez ME, Gastroenterology, Volume 136, Issue 3, March 2009.