Clinical role of multigenic prognostic tests in breast cancer therapy

Current clinical practice for breast cancer originates in “evidence based medicine”. In this, each tumor receives a therapy optimal for a given patient population – which might not be optimal for each individual patient. Multigenic tests determining expression of a set of genes can provide additional support in this decision process. Two such tests (MammaPrint and Prosigna) have already received FDA clearance. A number of additional test are commercially available (IHC4, Oncotype DX, EndoPredict, BCI). A common property of these assays is their utility in estrogen receptor positive early breast cancer. The main clinical problem answered by them is the necessity of adjuvant chemotherapy. To date, no reliable algorithm has been identifi ed capable to pinpoint the most effective chemotherapy combination for a given patient. Furthermore, there is no trustworthy test for triple negative breast cancer. The assays utilize different technologies (immunohistochemistry, gene chips, RT-PCR) and a discrepant list of genes – these result in discordance of the predictions for the individual patient. Despite these shortcomings, multigenic tests quickly gained foothold in breast cancer therapy decision process. Their utility is supported by the cost reduction for the health care providers by lowering the number of patients eligible for chemotherapy.