youtube New Breast Cancer Prognostic Test

FDA recently cleared for marketing a new test called the MammaPrint that can predict the odds that an early stage breast cancer will metastasize in five to ten years. Using a biopsy sample taken from the tumor, the test analyzes the activity of 70 genes which affect whether or not an early stage breast cancer will spread. Based on this, it rates the patient as "high risk" or "low risk" for metastases. MammaPrint is intended for women who are under 61 years old with Stage I or II disease who are lymph node-negative and whose tumors are no larger than 5 cm.

MammaPrint's reliability differs a great deal depending on which risk category it places the woman in. When the test designates the woman as "low risk," there is 90% probability that she will not get metastatic disease at 5 years. But when the test designates the woman as "high risk," there is only a 25% chance that she will actually develop distant metastases at 5 years. It is important for women and their physicians to understand this difference, and to keep the test's limitations in mind.

It is also important to keep in mind that the MammaPrint test is not intended to diagnose breast cancer, or to select the type of therapy, or to predict the woman's response to it. It is a prognostic marker only, to be used along with other clinico-pathological factors.

MammaPrint is currently available overseas. The test's developer, the Dutch company Agendia, is exploring ways to make the test available in the U.S.