Gene expression profiling in breast cancer

In recent years, molecular research has translated into remarkable changes of breast cancer diagnostics and therapeutics. Molecular tests such as the 21 gene expression test (Oncotype DXTM) and 70 gene microarray test (MammaPrint®) have revolutionized the predictive and prognostic tools in the clinic. By stratifying the risk of recurrence for patients, the tests are able to provide clinicians with more information on the treatment outcomes of using chemotherapy, HER2 targeted therapy or endocrine therapy or the combination of the therapies for patients with particular genetic expressions. However, it is still questionable for clinical applications as some areas remain unclear and that the true benefit still needs prospective evaluation. Such studies are under way and are anxiously awaited. In this paper, the limitation of the molecular tests are discussed. As we are moving towards personalized medicine, molecular profiling will not only result in better outcomes but in a certain proportion of patients, likely will spare unnecessary use of cytotoxic compounds and reduce the cost to the health care systems.