Differential clinicopathological features in microsatellite instability-positive colorectal cancers depending on CIMP status

Virchows Arch. 2011 Jul;459(1):55-63. doi: 10.1007/s00428-011-1080-3. Epub 2011 Apr 15.

Abstract

Microsatellite instability-positive (MSI+) colorectal cancers (CRCs) are divided into CpG island methylator phenotype-positive (CIMP+) and CpG island methylator phenotype-negative (CIMP-) tumors. The repertoire of inactivated genes in CIMP+/MSI+ CRCs overlaps with but is likely to differ from that of CIMP-/MSI+ CRCs. Because epigenotypic differences are likely to be manifested as phenotypic differences, CIMP+/MSI+ CRCs are expected to differ from CIMP-/MSI+ CRCs in some clinicopathological features. This study aimed to characterize both common and different features between the two subtypes. A total of 72 MSI+ CRCs were analyzed for their methylation status in eight CIMP panel markers using MethyLight assay. CIMP+/MSI+ and CIMP-/MSI+ CRCs were compared regarding clinicopathologic features and mutation in KRAS/BRAF. An independent set of MSI+ CRCs (n = 97) was analyzed for their relationship of CIMP+ status with clinical outcome. Eighteen cases (25%) were CIMP+, and this CIMP+ subtype was highly correlated with older age (P < 0.001). Polypoid gross appearance without ulceration was observed only in CIMP-/MSI+ CRCs (18.5%, P = 0.057). CIMP+/MSI+ CRCs were closely associated with poor differentiation, medullary appearance, signet ring cell appearance, and acinar-form appearance, whereas the CIMP-/MSI+ subtype was closely associated with intraglandular eosinophilic mucin and stratified nuclei (all P values <0.05). Patients with CIMP+/MSI+ CRCs showed worse overall survival than patients with CIMP-/MSI+ CRCs. Our results demonstrate heterogeneity in the clinicopathological features of MSI+ CRCs depending on CIMP status. The observation that CIMP+ and CIMP- subtypes showed different clinical behaviors may provide a clue for establishing subtype-specific therapeutic strategies for these two subtypes.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma / genetics*
  • Adenocarcinoma / mortality
  • Adenocarcinoma / pathology
  • Aged
  • Colorectal Neoplasms / genetics*
  • Colorectal Neoplasms / mortality
  • Colorectal Neoplasms / pathology
  • CpG Islands / genetics*
  • DNA Methylation
  • DNA, Neoplasm / analysis
  • Female
  • Genetic Markers
  • Humans
  • Male
  • Microsatellite Instability*
  • Middle Aged
  • Survival Rate

Substances

  • DNA, Neoplasm
  • Genetic Markers