The MammaPrint breast cancer test can dramatically reduce the number of women who need to undergo chemotherapy to treat the disease, according to a newly published study.
The prospective, outcome-based study of 427 breast cancer patients showed the genomic test, which analyzes 70 key genes, accurately determines which patients are at low risk of breast cancer recurrence and can therefore safely choose not to undergo chemotherapy.
Of the 219 patients in the five-year study who were determined to be "low risk" based on the MammaPrint test, 85 percent chose not to have chemotherapy. Of those patients, 97 percent were disease-free after five years. Of the 208 patients who were determined to be 'high risk," 81 percent chose chemotherapy and 91% were disease-free after five years.
"MammaPrint correctly stratified patients into Low Risk and High Risk categories based on prognosis of a recurrence of the disease," said Prof. S.C. Linn, M.D., the principal investigator. "The outcome data generated in the study confirmed it was safe for the Low Risk patients to choose not to undergo chemotherapy and still have excellent outcomes."
The results of the peer-reviewed study, called MicroarRAy PrognoSTics in Breast CancER (or RASTER), conducted in 16 community-based clinics in the Netherlands, were published online by The International Journal of Cancer and will later appear in the journal's print edition.
The RASTER study is considered unique by its co-authors because it is the first and only study to prospectively evaluate the performance of a genomic breast cancer test by using outcome data -- in this case through follow-up of the patient cohort for five years.
"The study showed that incorporating MammaPrint results along with the traditional clinical parameters will significantly reduce the number of women who need chemotherapy, allowing them to avoid the side effects and toxicity of treatment, some of which can be permanent and debilitating," said breast surgeon Alison Laidley, M.D., FACS with Texas Breast Specialists, Texas Oncology (Dallas).