Microsatellite instability in colorectal cancer: improved assessment using fluorescent polymerase chain reaction

Gastroenterology. 1995 Aug;109(2):465-71. doi: 10.1016/0016-5085(95)90334-8.


Background & aims: Microsatellite instability was first described in hereditary nonpolyposis colorectal cancers and sporadic colorectal cancers, in which it was associated with a good prognosis. The aim of this study was to assess the advantages of a novel fluorescent assay for detecting microsatellite instability.

Methods: Eleven fluorescently tagged microsatellites and an automated DNA sequencer were used to investigate 54 sporadic colorectal adenocarcinomas.

Results: This fluorescent assay combined accurate allele sizing with cross-sectional data display and allowed improved assessment of microsatellite instability. Twenty-two percent of cancers (12 of 54) showed microsatellite instability with at least one marker. For tumors showing microsatellite instability, results were obtained for a minimum of eight markers. Six tumors showed microsatellite instability at high frequency (at least 63% of markers affected), and 42% of the patients who had a tumor showing microsatellite instability had a synchronous and/or metachronous colorectal tumor (vs. 7% of patients whose tumor did not show microsatellite instability). Patients with a microsatellite instability-positive tumor had an improved prognosis (P = 0.03).

Conclusions: The use of this fluorescent assay improved the assessment of microsatellite instability with the automated analysis and cross-sectional data display. The assay identified a subgroup of patients who showed microsatellite instability and who also showed clinical features that differed from the microsatellite instability-negative cases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma / genetics*
  • Aged
  • Alleles
  • Colorectal Neoplasms / genetics*
  • DNA, Satellite*
  • Female
  • Fluorescence
  • Humans
  • Image Interpretation, Computer-Assisted
  • Polymerase Chain Reaction*
  • Prognosis


  • DNA, Satellite