Some individuals are diagnosed with colorectal cancer despite recent colonoscopy.
Dr Douglas Robertson and colleagues examined individuals under colonoscopic surveillance for colonic adenomas to assess possible reasons for diagnosing cancer after a recent colonoscopy with complete removal of any identified polyps.
Primary data were pooled from 8 large North American studies in which participants with adenoma(s) had a baseline colonoscopy and were followed with subsequent colonoscopy.
The research team used an algorithm based on the time from previous colonoscopy and the presence, size and histology of adenomas detected at prior exam to assign interval cancers as likely being new, missed, incompletely resected or due to failed biopsy detection.
The team included 9167 participants in the analyses, with a median follow-up of 47 months.
Invasive cancer was diagnosed in 58 patients during follow-up.
|The cancer diagnosis may have been delayed in 5% of cases because of failed biopsy detection|
The team observed that 78% of cancers were early stage, however, 16% resulted in death from colorectal cancer.
The researchers classified 52% of cancers as probable missed lesions, 19% as possibly related to incomplete resection of an earlier, non-invasive lesion, and 24% as probable new lesions.
The cancer diagnosis may have been delayed in 5% of cases because of failed biopsy detection.
Dr Robertson's team concludes, "Despite recent colonoscopy with intent to remove all neoplasia, colorectal cancer will occasionally be diagnosed."
"These cancers primarily seem to represent lesions that were missed or incompletely removed at the prior colonoscopy, and might be avoided by increased emphasis on identifying and completely removing all neoplastic lesions at colonoscopy."