title: Evaluation of colonoscopic sized biopsies for microsatellite instability and adenomatous polyposis coli (APC) variants.
abstract: OBJECTIVE
  Knowledge of certain genetic changes associated with the development of colorectal cancer may influence surgical treatment in the future. Cancers are known to show intratumoural genetic heterogeneity. The aim of this study was to determine whether colonoscopic sized biopsies provide enough tissue to overcome the effects of tumour heterogeneity for the results of genetic analysis to be representative of the tumour as a whole.
  
  
  METHODS
  Using colonoscopic biopsy forceps, samples were taken from 30 resected colorectal cancers and investigated for microsatellite instability (MSI) at five loci and changes in the adenomatous polyposis coli gene (APC) by single-stranded conformational polymorphism analysis. Identical genetic analysis was carried out on larger specimens taken from each of these cancers to determine whether the molecular findings from the large specimen were the same as those from colonoscopic sized biopsies.
  
  
  RESULTS
  The microsatellite instability and APC status of the colonoscopic sized biopsies and those from larger specimens were completely consistent.
  
  
  CONCLUSIONS
  These results suggest that colonoscopic sized biopsies are reliable in determining the MSI status and APC variants of individual colorectal cancers.
authors.affiliation: Department of Surgery, Royal Free and University College Medical School, London, UK.
authors.lastname: Sengupta
authors.lastname: Pearson
authors.lastname: Yiu
authors.lastname: Boulos