title: Next-generation sequencing in breast cancer:  first take home messages.
abstract: OBJECTIVE
  We are currently on the threshold of a revolution in breast cancer research, thanks to the emergence of novel technologies based on next-generation sequencing (NGS). In this review, we will describe the different sequencing technologies and platforms, and summarize the main findings from the latest sequencing articles in breast cancer.
  
  
  RESULTS
  Firstly, the sequencing of a few hundreds of breast tumors has revealed new cancer genes. Although these were not frequently mutated, mutated genes from different patients could be grouped into the deregulation of similar pathways. Secondly, NGS allowed further exploration of intratumor heterogeneity and revealed that although subclonal mutations were present in all tumors, there was always a dominant clone, which comprised at least 50% of the tumor cells. Finally, tumor-specific DNA rearrangements could be detected in the patient's plasma, suggesting that NGS could be used to personalize the monitoring of the disease.
  
  
  CONCLUSIONS
  The application of NGS to breast cancer has been associated with tremendous advances and promises for increasing the understanding of the disease. However, there still remain many unanswered questions, such as the role of structural changes of tumor genomes in cancer progression and treatment response/resistance.
authors.affiliation: Breast Cancer Translational Laboratory, Université Libre de Bruxelles, Jules Bordet Institute, Brussels, Belgium. christine.desmedt@bordet.be
authors.forename: Christine
authors.initials: C
authors.lastname: Desmedt
authors.forename: Thierry
authors.initials: T
authors.lastname: Voet
authors.forename: Christos
authors.initials: C
authors.lastname: Sotiriou
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Campbell
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D030541:Databases, Genetic; D005260:Female; D020869:Gene Expression Profiling; D056726:Genetic Association Studies; D018740:Genetic Heterogeneity; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D057285:Precision Medicine; D017422:Sequence Analysis, DNA; D017423:Sequence Analysis, RNA