Genetic instability in patients with metachronous colorectal cancers

Background Nearly 7 per cent of patients who undergo resection for colorectal cancer develop metachronous cancers several years later. A molecular marker that could identify patients susceptible to metachronous cancers would be of clinical importance. Methods Twenty-four colorectal cancers from 15 individuals with metachronous colorectal cancer were investigated for microsatellite instability at five loci by single stranded conformational polymorphism analysis. A control group of 14 colorectal cancers from individuals who had only developed one sporadic colorectal cancer each was analysed similarly. Results Microsatellite instability was demonstrated in 17 of 24 cancers from individuals with metachronous cancer compared with one of 14 cancers from individuals with a single colorectal cancer. Conclusion These results suggest that testing for microsatellite instability may be useful in recognizing patients at high risk of developing metachronous colorectal cancers.