Use of a genomic test (MammaPrint™) in daily clinical practice to assist in risk stratification of young breast cancer patients

Abstract

Breast cancer as a heterogeneous disease demands reliable tools in order to identify those patients who most likely will benefit from receiving adjuvant treatment, such as chemotherapy. The MammaPrint test was established on the basis of a 70-gene expression profile. In this prospective study, the adaptation of MammaPrint™ into clinical work-up procedures was investigated in 56 patients with an average age of 45 years treated at a general hospital in Germany between 2004 and 2008. To assess the accuracy of MammaPrint in this younger patient group, a meta-analysis was performed on a subgroup from previously described retrospective studies (n = 689). 44 patients had MammaPrint results and were eligible for the analysis. The results revealed a low risk result in 29 patients and a high risk result in 15 patients. Using St. Gallen 2007 guidelines for risk assessment, the numbers were 4 for low risk and 6 for high risk, respectively, while 34 patients were classified as intermediate risk. In the group of women with intermediate risk, MammaPrint assigned 23 patients to low risk and 11 to the high risk group. In the meta-analysis of retrospective studies, 10 year overall survival for the low and high MammaPrint groups was 90.2 and 65.2%, respectively. Using gene expression analysis as additional tool, patients with an intermediate clinical risk can be accurately separated into low and high risk groups. The gene expression analysis provides more accurate information on recurrence risk compared to conventional clinicopathological criteria and thus may provide additional guidance in daily clinical practice in future. Results of further prospectively designed studies like the MINDACT trial will confirm the retrospective analysis and will determine how both low and high risk patients can best be treated.