Abstract
Objective: To identify colorectal cancers occurring after colonoscopic screening in patients at risk for Lynch syndrome. Methods: All cancers in Lynch syndrome families on file at the Creighton University Hereditary Cancer Institute were reviewed for history of prior colonoscopy. Results: Of 225 individuals with 313 colon cancers, six patients from different families had colon cancers arising within 4 1/2 yr of colonoscopic surveillance. Another 17 patients had metachronous colon cancers within 5 yr of resection of their first colon cancer. Conclusion: Of 225 colorectal cancer patients from Lynch syndrome families, 10.2% of patients had colorectal cancer within 5 yr of colonoscopy or colon resection. In Lynch syndrome, the potential for interval neoplasms and the malignant potential of missed diminutive adenomas may differ from cases in the general population.