Researchers studied the rate of interval colorectal cancer in 1,297 patients participating in the Polyp Prevention Trial Continued Follow-up Study, a study that followed patients participating in the Polyp Prevention Trial. The PPT-CFS was designed to determine the rate of interval colorectal cancer after the PPT and to examine the circumstances surrounding incidences of cancer, according to the release.
In the study, nine cases of colorectal cancer were diagnosed over 7,626 person-years of observation for an incidence rate of 1.2 per 1,000 person-years of observation. According to the release, 78 percent had a history of advanced adenoma, and most of the cancers detected were early stage (78 percent were stage I or II) and therefore highly curable.
Eight out of the nine cancers were located in the proximal colon, where studies have suggested that colonoscopy is less successful in detection, according to the release. Researchers also found that 78 percent of the new colorectal cancer cases diagnosed during the PPT-CFS were diagnosed in men and 44 percent had a family history of colorectal cancer.
Many explanations for the interval cancers were proposed, including four cancers found in colon segments where a polyp was previously found, two cancers attributed to incomplete removal of a previous adenoma and two cancers where biopsy failed to detect a neoplastic lesion, according to the release.
According to the release, the study highlights the importance of quality colonoscopy screening, including the importance of proper bowel prep and adequate length of colonoscopy in order to detect all polyps that may be present.
Read the release about incidence of interval colorectal cancer in colonoscopy (pdf).
