[Molecular alterations in breast cancer: clinical implications and new analytical tools]

Breast cancer is a complex and heterogeneous disease resulting from various molecular alterations, the identification of which should have profound impact on the management of patients.

The discovery of germline mutations within breast cancer susceptibility genes, such as BRCA1 and BRCA2, which are associated with a major risk of breast cancer during lifetime, has improved the assessment of the individual risk toward the disease, allowing appropriate strategies of screening and prevention. The identification of key molecular actors in the mammary oncogenesis may help to better assess the prognosis of the disease, while providing new therapeutic targets. Large-scale molecular technologies, which allow simultaneous assessment of a high number of molecular parameters in a single assay, should provide new tools to tackle complexity and heterogeneity of breast cancer. Hence, by examining transcriptional profiles of breast cancer using DNA microarrays, it was possible to reveal new prognostic tumor subgroups, previously indistinguishable. Further improvements are awaited with the recent development of high throughput and large-scale technologies investigating the tumor proteome.

Precise knowledge of molecular alterations involved in each individual breast cancer will allow more effective and less toxic, tailored therapies.