Phe significance of microsatellite instability in predicting the development of metachronous multiple colorectal carcinomas in patients with nonfamilial colorectal carcinoma

BACKGROUND. Patients with metachronous multiple colorectal carcinomas have been reported to have a higher frequency of a family history of colorectal carcinoma, associated colorectal adenomas, and extracolonic malignancies. T hese clinicopathologic factors also are considered to be related to the dev elopment of metachronous multiple colorectal carcinomas after surgery for c olorectal carcinoma. In this article, the authors investigated whether gene tic markers such as microsatellite instability (MSI) were helpful in predic ting the development of metachronous multiple colorectal carcinomas. METHODS, Between 1990-1997, 312 colorectal carcinoma patients underwent yea rly surveillance colonoscopy after surgery. Among these patients, there wer e 19 with nonfamilial colorectal carcinoma in whom metachronous multiple co lorectal carcinomas were diagnosed during the yearly surveillance colonosco py. A control group was comprised of 28 patients who did not demonstrate ei ther synchronous or metachronous carcinomas over a period of greater than o r equal to 5 years. Six microsatellite markers (D2S123, D3S1029, D3S1611, T P53, Mfd26, and Mfd36) were used to determine MSI by polymerase chain react ion. RESULTS. The frequency of MSI positive cases was significantly higher in pa tients with sporadic metachronous multiple colorectal carcinomas than in th ose with a single carcinoma (17/19 [89%] vs. 4/28 [14%]; P < 0.0001). In tu mors occurring in the distal colon and rectum, the percentage of MSI positi ve carcinomas was significantly higher in the patients with metachronous mu ltiple carcinomas than in those with a single carcinoma (13/15 [87%] vs. 0/ 19 [0%]; P < 0.0001). No such difference was observed in the proximal colon . CONCLUSIONS. Based on the findings of the current study, the analysis of MS I in sporadic carcinomas of the distal colon and rectum may be helpful in p redicting the development of metachronous multiple colorectal carcinomas. ( C) 1999 American Cancer Society.