Dec. 7, 2010 Among patients with a family or past history of colorectal cancer (CRC), testing between colonoscopies helps detect CRC and advanced tumors that are either missed or develop rapidly, according to a new study in Gastroenterology, the official journal of the American Gastroenterological Association (AGA) Institute.
"By using fecal immunochemical testing -- a new type of stool blood test -- in the interval between surveillance colonoscopies, we were able to detect cancer much sooner than if we had waited for the scheduled surveillance," said Graeme P. Young, MD, AGAF, FRACP, of Flinders Medical Centre, Australia and lead author of the study. "In fact, in those patients who consistently returned a negative fecal immunochemical test, the chance of finding cancer or advanced adenoma was significantly reduced."
A joint guideline from the American Cancer Society, the U.S. Multi-Society Task Force on Colorectal Cancer and the American College of Radiology recommends that average-risk adults, beginning at the age of 50, should receive a colonoscopy every ten years and that annual fecal immunochemical tests (FIT) are acceptable choices for CRC screening in between this ten-year span (any positive FIT should be followed up with a colonoscopy). Guidelines suggest more frequent colonoscopies for certain high-risk groups.
In this study, 1,736 patients with a confirmed family or personal history of CRC were followed for 8,863 person years of surveillance; some for as long as 20 years. The study inclusion criteria required that patients had received at least an initial and one subsequent surveillance colonoscopy with adequate examination and retrieval of tissue, performed with a training-accredited colonoscopist present. In the 1,071 asymptomatic subjects who returned at least one FIT after the colonoscopies, the test detected 12 out of 14 cancers and 60 out of 96 advanced adenomas. In FIT-positive cases, the diagnosis was made sooner by 25 months for cancer and by 24 months for advanced adenomas before the regularly scheduled colonoscopy.
"Our study results suggest that interval fecal immunochemical testing in a high-risk colonoscopy program can be used for detecting missed or rapidly developing lesions," added Dr. Young.
Patients at increased risk for developing CRC due to a family history or past history of CRC are recommended to have colonoscopic surveillance at regular intervals, often more frequently than recommended for the average-risk population. Patients with only one or two small adenomas with low-grade dysplasia are recommended to have their second surveillance colonoscopy after an interval of 10 years. However, for these individuals, there is a greater risk of delay in detecting rapidly progressing or missed lesions. Using annual fecal occult blood tests in the interval between surveillance colonoscopies could be a strategy that helps manage this risk. FIT, which uses an antibody specific for human hemoglobin, is being increasingly used because it is more sensitive for cancer and adenomas.
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