MYC amplification in breast cancer: a chromogenic in situ hybridisation study

J Clin Pathol. 2007 Sep;60(9):1017-23. doi: 10.1136/jcp.2006.043869. Epub 2006 Dec 8.

Abstract

Aims: To analyse the correlation between MYC amplification and various clinicopathological features and outcome in a cohort of 245 patients with invasive breast carcinoma treated with surgery followed by anthracycline-based chemotherapy. Given the high prevalence of MYC amplification in tumours of BRCA1 mutation carriers and the similarities between these and sporadic "basal-like" carcinomas, the prevalence of MYC amplification in "basal-like" breast carcinomas was investigated.

Methods: MYC gene copy number was assessed on tissue microarrays containing duplicate cores of 245 invasive breast carcinomas by means of chromogenic in situ hybridisation using SpotLight C-MYC amplification probe and chromosome 8 centromeric probe (CEP8). Signals were evaluated at 400x magnification; 30 morphologically unequivocal neoplastic cells in each core were counted for the presence of the gene and CEP8 probes.

Results: Amplification was defined as a MYC:CEP8 ratio >2. Signals for both MYC and CEP8 were assessable in 196/245 (80%) tumours. MYC amplification was found in 19/196 cases (9.7%) and was not associated with tumour size, histological grade, positivity for oestrogen receptor, progesterone receptor, HER2, epidermal growth factor, cytokeratins 14, 5/6 and 17, MIB1 or p53. Only 4% of basal-like carcinomas showed MYC amplification, compared to 8.75% and 10.7% of luminal and HER2 tumours respectively. On univariate analysis, MYC amplification displayed a significant association with shorter metastasis-free and overall survival and proved to be an independent prognostic factor on multivariate survival analysis.

Conclusion: MYC amplification is not associated with "basal-like" phenotype and proved to be an independent prognostic factor for breast cancer patients treated with anthracycline-based chemotherapy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anthracyclines / therapeutic use
  • Antineoplastic Agents / therapeutic use
  • Breast Neoplasms / genetics*
  • Breast Neoplasms / therapy
  • Chemotherapy, Adjuvant
  • Chromogenic Compounds
  • Female
  • Gene Amplification / genetics
  • Genes, myc*
  • Humans
  • Mastectomy
  • Prognosis
  • Survival Analysis
  • Tissue Array Analysis / methods
  • Treatment Outcome

Substances

  • Anthracyclines
  • Antineoplastic Agents
  • Chromogenic Compounds