Developing a molecular marker for metachronous colorectal cancer.

ABSTRACT

OBJECTIVE: To determine the prevalence of microsatellite instability in patients with metachronous colorectal cancer as a potential marker for identification of high risk individuals. SETTING: Surgical research laboratory, Whittington Hospital, Highgate Hill, London. SUBJECTS AND METHODS: 37 colorectal tumours from 18 individuals with metachronous colorectal cancers were investigated at five microsatellite loci by single stranded conformational polymorphism (SSCP) analysis. A control group of 11 individuals who had developed one sporadic colorectal cancer each were also similarly analysed. MEASUREMENTS Tumour microsatellite instability was defined as the appearance of new polymarase chain reaction (PCR) bands, either larger or smaller than those produced from the normal mucosa. RESULTS: 27 of the total of 37 metachronous cancer specimens PCR amplified successfully. Microsatellite instability was demonstrated in 59.3% (16/27) of individuals with metachronous tumours. None of the tumours in the control group showed microsatellite instability. CONCLUSIONS: These results suggest that individuals with colorectal cancer with replication errors are at a greater risk of developing metachronous colorectal cancer than those without replication errors.