van de Vijver M.J.: Genetic alterations and gene expression profiles of solid tumors

Breast cancer is presently classified based on tumor diameter, histologic type and grade, lymph node status and estrogen receptor, progesterone receptor and HER2 status. This classification has important implications for the treatment of breast cancer patients.
A more refined classification should be possible based on genetic alterations and gene expression profiles.
The genetic alterations identified in breast cancer are amplification of between 10 and 20 oncogenes and mutations in tumor suppressor genes.
We have studied the genetic alterations (with a focus on HER2 gene amplification) in breast carcinomas in relation to clinical and pathological parameters.
Gene expression profiling has led to the identification of subsets of breast cancer revealed by unsupervised and supervised classification.
We have used supervised classification to identify a 70 gene prognosis profile and clinical studies are ongoing to investigate if and how this prognosis profile can be implemented in clinical practice.
In addition, our research is aimed at identifying genetic profiles associated with response to specific therapies.
The aims of our studies are to understand the development of breast cancer at the molecular level; and to use this knowledge in treating individual breast cancer patients.