Colon tumor
Molecular pathways
Chromosome instability pathway

Topic Completed: 1 September 2010

Revised: 9 January 2019, last major update September 2010

Copyright: (c) 2003-2016,, Inc.

PubMed Search: Chromosome AND "instability pathway"

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Cite this page: Jain S. Chromosome instability pathway. website. Accessed May 20th, 2019.
Definition / general
  • Common pathway in colorectal carcinoma
  • Mutations in oncogenes and tumor suppressor genes, including APC, beta catenin, Kras, BRAF, SMAD4, PTEN, p53 and bax
  • Have altered total DNA content, cytogenetics, aneuploidy and numerous allelic gains and losses and translocations
Clinical features
  • Important in familial adenomatous polyposis and variants (APC gene) and juvenile polyposis (DPC4, PTEN genes)
  • High rate of concordance for Kras status between primaries and metastases (Oncologist. 2008;13:1270)
  • Patterns of Kras mutation vary based on germline mismatch repair defects and hMLH1 methylation status (Hum Mol Genet 2004;13:2303)
  • Updated National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines in Oncology for Colon Cancer now recommend that tumors from all patients with stage IV disease be tested for the Kras gene
  • Only patients whose tumors have normal (wild type) Kras should receive cetuximab and panitumumab
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