Breast Cancer and Chemotherapy

When it comes to responding to chemotherapy, not all breast cancers are created equal. So far, doctors have not been able to accurately predict which women would derive added benefits from chemotherapy and which ones wouldn't. So the policy has often been, "When in doubt, get chemotherapy."

Now, studies show that a new genetic test, known as the Oncotype DX 21-gene assay, not only assesses the likelihood of breast cancer recurrence for many early-stage breast cancer patients, but also predicts how much chemotherapy will help these women. This new test may give some low-risk women the option of skipping the rigors of chemotherapy, while reassuring others that the often-difficult treatment they're receiving has a clearly defined benefit.

For women who have hormone-positive breast cancer that has not yet spread to the lymph nodes, the Oncotype assay analyzes 21 genes related to breast cancer in the body that breast cancer cells depend on, including the estrogen receptor, HER2 and proliferation genes. It then divides the results into low-, medium-, and high-risk scores.

Women in the low-risk group, about half the patients studied, would get only a minimal, if any, benefit from chemotherapy. Women in the high-risk group would be very likely to benefit from chemotherapy.