Clinical Management of Lynch Syndrome: Revised Guidelines
Clinical Management of Lynch Syndrome: Revised Guidelines
What is the optimal colorectal surveillance protocol for LS?
Colorectal surveillance is the only surveillance protocol in LS proved to be effective. Regular colonoscopy leads to a reduction of CRC-related mortality and also to a significant reduction of overall mortality in contrast with CRC screening in the general population.
However, there is an ongoing discussion about the optimal interval between colonoscopic examinations. Although a 3-year interval between colonoscopies has been proved to be effective, there are no studies that have compared the effectiveness between different intervals. Since 2007, three prospective studies and one retrospective study analysing the effectiveness of colonoscopic surveillance have been published. The characteristics of the study populations, the intervals that were recommended and the outcomes are summarised in Table 4.
Unfortunately, it is difficult to compare the risks of developing an interval cancer (defined as a cancer that develops after a negative screening examination) between the studies due to the different methodologies used. The proportion of interval cancers with a local tumour (stages I and II) varied from 78% to 95%. Most tumours (57–62%) were located in the right colon, which emphasises the importance of careful investigation of this part of the colon. In the Dutch, German and Canadian series, most interval cancers were diagnosed in individuals older than 40 years. However, in the Finnish series a substantial proportion (20–30%) were diagnosed between the age of 30 and 40 years. In one study, the influence of the type of MMR gene defect on the risk of developing interval cancers was evaluated. That study demonstrated that the risk was lower for carriers of an MSH6 gene mutation, although the difference was not statistically significant.
In the Finnish series, it was found that mortality due to CRC was associated with a lack of participation in the surveillance programme. This is concerning given that the lack of compliance with the recommended surveillance interval in the German and Canadian studies was 20% and 42%. To guarantee the continuity of surveillance and improve compliance with the surveillance recommendations patients should be registered at a regional or national hereditary cancer registry. Such registries can improve participation in surveillance by using reminder systems.
A 3-year interval between colonoscopies has been proved to be effective (category of evidence IIb). In view of the observation of (advanced) CRC detected between 2 and 3 years after surveillance colonoscopy, the recommended interval for mutation carriers is 1–2 years (grade of recommendation C).
Question No 2
What is the optimal colorectal surveillance protocol for LS?
Relevant Literature
Colorectal surveillance is the only surveillance protocol in LS proved to be effective. Regular colonoscopy leads to a reduction of CRC-related mortality and also to a significant reduction of overall mortality in contrast with CRC screening in the general population.
However, there is an ongoing discussion about the optimal interval between colonoscopic examinations. Although a 3-year interval between colonoscopies has been proved to be effective, there are no studies that have compared the effectiveness between different intervals. Since 2007, three prospective studies and one retrospective study analysing the effectiveness of colonoscopic surveillance have been published. The characteristics of the study populations, the intervals that were recommended and the outcomes are summarised in Table 4.
Unfortunately, it is difficult to compare the risks of developing an interval cancer (defined as a cancer that develops after a negative screening examination) between the studies due to the different methodologies used. The proportion of interval cancers with a local tumour (stages I and II) varied from 78% to 95%. Most tumours (57–62%) were located in the right colon, which emphasises the importance of careful investigation of this part of the colon. In the Dutch, German and Canadian series, most interval cancers were diagnosed in individuals older than 40 years. However, in the Finnish series a substantial proportion (20–30%) were diagnosed between the age of 30 and 40 years. In one study, the influence of the type of MMR gene defect on the risk of developing interval cancers was evaluated. That study demonstrated that the risk was lower for carriers of an MSH6 gene mutation, although the difference was not statistically significant.
In the Finnish series, it was found that mortality due to CRC was associated with a lack of participation in the surveillance programme. This is concerning given that the lack of compliance with the recommended surveillance interval in the German and Canadian studies was 20% and 42%. To guarantee the continuity of surveillance and improve compliance with the surveillance recommendations patients should be registered at a regional or national hereditary cancer registry. Such registries can improve participation in surveillance by using reminder systems.
Conclusion
A 3-year interval between colonoscopies has been proved to be effective (category of evidence IIb). In view of the observation of (advanced) CRC detected between 2 and 3 years after surveillance colonoscopy, the recommended interval for mutation carriers is 1–2 years (grade of recommendation C).