Introduction: Lynch syndrome families have a substantial risk of developing colorectal cancer (CRC). The recommended surveillance protocol includes colonoscopy every 2 years from age 20-25 years. It is yet unknown whether annual screening of patients aged 40-60 years is more effective than bi-annual screening, whether patients who had an adenoma removed should be re-examined after a year and whether surveillance of second-degree relatives is indicated. The aim of this study was to address these issues.
Methods: All carriers of a mismatch repair gene mutation who participated in the surveillance program were selected from the Dutch Lynch syndrome registry. The results of colonoscopy were prospectively collected.
Results: A total of 666 mutation carriers were identified in 110 families. Fourty-one CRCs were detected during endoscopic follow-up, of which 34 (83%) were diagnosed between age 40 and 60 years. In five of 34 patients, CRC was diagnosed within 1 year after colonoscopy, eight cancers were diagnosed between 1 and 2 years and the remaining tumors more than 2 years after colonoscopy. All eight CRCs detected between 1 and 2 years were at local stage. At least one adenoma was diagnosed at 141 examinations. The risk of developing CRC during follow-up in carriers with an adenoma was similar as in carriers without an adenoma at the previous colonoscopy. 280 parent-child couples with at least one Lynch syndrome-related carcinoma were identified in 110 families. In only 19 (6.8%) of these couples, CRC developed earlier in the child than an Lynch syndrome-associated cancer in the parent.
Conclusion: The current surveillance protocol, i.e., bi-annual colonoscopy in first-degree relatives independent of age and endoscopic findings, appears to be appropriate.