Cancer Causes & Control

, Volume 20, Issue 9, pp 1763–1768

Microsatellite instability and survival in rectal cancer

Authors

    • Department of PathologyUniversity of Utah Health Sciences Center
  • Karen Curtin
    • Department of Internal MedicineUniversity of Utah Health Sciences Center
  • Roger K. Wolff
    • Department of Internal MedicineUniversity of Utah Health Sciences Center
  • Sheryl R. Tripp
    • Department of PathologyUniversity of Utah Health Sciences Center
  • Bette J. Caan
    • Division of ResearchKaiser Permanente Medical Care Program
  • Martha L. Slattery
    • Department of Internal MedicineUniversity of Utah Health Sciences Center
Brief report

DOI: 10.1007/s10552-009-9410-3

Cite this article as:
Samowitz, W.S., Curtin, K., Wolff, R.K. et al. Cancer Causes Control (2009) 20: 1763. doi:10.1007/s10552-009-9410-3

Abstract

Objective

High levels of microsatellite instability (MSI-H) have been associated in many studies with improved prognosis in colon cancer. Very few studies have evaluated the effect of MSI-H on rectal cancer survival. We assessed MSI-H and other genetic and epigenetic changes on survival of 990 individuals diagnosed with first primary rectal cancer.

Methods

MSI was assessed primarily by instability in the mononucleotide repeat BAT-26. The BRAF V600E mutation was assessed by TaqMan assay. The CpG island methylator phenotype (CIMP) was determined by methylation-specific PCR of CpG islands in MLH1, methylated in tumors (MINT)1, (MINT)2, (MINT)31 and CDKN2A. KRAS2 codons 12 and 13 mutations, and TP53 mutations in exons 5–8 were determined by sequencing.

Results

Multivariate analysis revealed that MSI-H (HRR 2.47, 95% CI 1.13–5.40) and KRAS2 mutations (HRR 1.37, 95% CI 1.04–1.81) were associated with a significantly higher risk of dying of rectal cancer. Only one of 22 MSI-H tumors showed a BRAF V600E mutation. Of 15 MSI-H rectal cancers evaluated for methylation, two exhibited MLH1 methylation and four exhibited CIMP.

Conclusion

The genetic and epigenetic characteristics of MSI-H rectal cancers suggest that they are enriched for Lynch-associated tumors; adverse prognosis associated with MSI-H in these tumors may reflect the relatively high frequency of Lynch-associated cancers and/or the effect of radiation or chemotherapy on Lynch-associated rectal cancers or MSI tumors in general.

Keywords

Colorectal cancerMicrosatellite instabilityLynch syndromeSurvivalHereditary nonpolyposis colorectal cancer

Abbreviations

CIMP

CpG island methylator phenotype

HNPCC

Hereditary nonpolyposis colon cancer

PCR

Polymerase chain reaction

OR

Odds ratio

CI

Confidence interval

Copyright information

© Springer Science+Business Media B.V. 2009