Predicting Breast Cancer's Return

Feb. 7, 2007— -- Tuesday's announcement by the U.S. Food and Drug Administration that it had approved the MammaPrint test represents a step forward in our efforts to more precisely define which women with breast cancer require adjuvant (preventive) chemotherapy following primary treatment for the disease.

Adjuvant chemotherapy for breast cancer has been one of the great success stories in cancer treatment over the past 30 years. Through the efforts of many researchers, women and their families, we have learned how to prevent recurrence of breast cancer and increase survival for many women with breast cancer. As a result, we have seen steady declines in the death rates for women with breast cancer.

We also know that we provide adjuvant chemotherapy to many women with primary breast cancer who would have otherwise done well without additional treatment. But the types of tests and information about a particular woman's breast cancer that we have available today are simply too imprecise to allow us to accurately and confidently separate women at high risk of developing recurrent of breast cancer from those who are at low risk of recurrence.

If we could do this, we could potentially avoid chemotherapy in the low-risk women, and thus free them from the need to take adjuvant chemotherapy along with its associated costs, inconvenience and side effects.

Over the past several years, there have been several tests developed that have moved us closer to predicting which women with breast cancer have the best chances of survival, and those who would likely benefit from chemotherapy.

A recent study in the August 10, 2006, issue of New England Journal of Medicine reviewed the performance of several of these various breast cancer prognostic tests (including MammaPrint). The researchers reported that although the fundamental approaches of the tests were different, several of them had similar outcomes when predicting which women had the greatest likelihood of developing recurrent breast cancer.