Identification of subjects at risk for colorectal carcinoma through a test based on K-ras determination in the stool

Gastroenterology. 1996 May;110(5):1346-53. doi: 10.1053/gast.1996.v110.pm8613038.


Background & aims: The gold standard for screening for colorectal carcinoma is colonoscopy. The aim of this study was to compare endoscopic results with those obtained using the noninvasive screening test of K-ras determination in the stool in a large population of patients undergoing colonoscopy.

Methods: Two hundred thirty consecutive patients were studied by K-ras amplification on stool-derived DNA using polymerase chain reaction and oligomer-specific hybridization.

Results: Wild-type K-ras was amplified in 103 of 230 patients (44.8%), the rate of amplification being directly proportional to the presence of an organic disease of the intestine characterized by hyperproliferating mucosa. In 30 of these 103 patients (29.1%), a K-ras mutation was found. Four of 5 with early colorectal carcinoma, all who had K-ras mutations in the tumor, were identified. In first-degree relatives of patients with colorectal carcinoma, all subjects either carrying adenomas > 1 cm in diameter or multiple smaller adenomas were identified. In patients with inflammatory bowel disease, the test identified the only patient with neoplastic transformation.

Conclusions: The sensitivity and specificity of K-ras determination on stool-derived DNA in patients with colorectal carcinoma, in first-degree relatives of patients with colorectal carcinoma, and in patients with inflammatory bowel disease support the opportunity of a large-scale trial to validate its use as a screening test.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenoma / genetics
  • Adenoma / prevention & control
  • Adult
  • Aged
  • Base Sequence
  • Colonoscopy
  • Colorectal Neoplasms / genetics*
  • Colorectal Neoplasms / prevention & control
  • DNA Mutational Analysis
  • Feces / chemistry*
  • Female
  • Gene Amplification
  • Genes, ras / genetics*
  • Humans
  • Inflammatory Bowel Diseases / genetics
  • Male
  • Mass Screening / methods
  • Middle Aged
  • Molecular Sequence Data
  • Mutation
  • Polymerase Chain Reaction
  • Predictive Value of Tests
  • Risk Assessment
  • Sensitivity and Specificity