There are three basic subtypes of breast cancer: hormone receptor-positive, triple-negative, and HER2-positive.
Except for the very smallest cancers in the early stages, when cancer hasn’t spread to the lymph nodes, most people with triple-negative and HER2-positive breast cancer require chemotherapy to give them the best chance of not having their cancer return.
In hormone receptor-positive breast cancer, the patients can benefit greatly from anti-estrogen medications, and chemotherapy may have less of a role.
If chemotherapy isn’t going to reduce the patient’s risk of recurrence, then surely one would want to avoid it. Chemotherapy has significant toxicities including, but not limited to:
- low blood counts
- nausea
- vomiting
- hair loss
- numbness and tingling of hands and feet
- induction of menopause in some premenopausal women
- slightly increased lifetime risk of leukemia for certain chemotherapy agents
Several factors are used to determine the need for chemotherapy for early stage breast cancer. The size of the cancer and whether the cancer has spread to the lymph nodes are two of the clinical features that are used.
Hormone receptor status is also a strong determinant of the need for chemotherapy. While many people with HER2-positive and triple-negative breast cancer do require chemotherapy, we can safely avoid chemotherapy in some people with hormone receptor-positive breast cancer.
The Oncotype DX test analyzes genes in cancer cells to help determine whether cancer will spread or reappear, and whether chemotherapy is needed in addition to anti-estrogen medications to reduce the chance of cancer spreading or returning.
You may be eligible for the Oncotype DX Breast Recurrence Score test if you have early stage, estrogen receptor-positive (ER-positive), or HER2-negative breast cancer. This test is a huge advance because it does allow many people with this subtype of breast cancer to skip chemotherapy.
In some instances, for ER-positive breast cancer, if the Oncotype DX shows chemotherapy would not be beneficial, skipping chemotherapy will not raise the risk of recurrence.
In ER-positive breast cancer, if the Oncotype DX is in the range where there isn’t a chemotherapy benefit, anti-estrogen medications will be used to reduce the risk of recurrence. These medications include aromatase inhibitors and tamoxifen.
Every type of cancer is different, and the indications for chemotherapy vary widely among different types of cancers.
It is so important to give a person every opportunity to avoid developing stage 4 breast cancer, so the benefit of chemotherapy should not be overlooked. However, the emergence of precision medication using a genomic profile like the Oncotype DX or a Mammaprint test can tell us who truly does benefit from chemotherapy, making overtreatment less of a concern moving forward.
In the future, there will likely be an expansion of the use of genomic profiling to fully understand the risk of recurrence and the benefits of various therapies. We may begin to see this profiling used for more advanced early breast cancer, such as stage 3.
Dr. Amy Tiersten is an ABMS board certified medical oncologist specializing in breast and gynecologic cancers. She is a professor of medicine and the clinical director of breast medical oncology at the Mount Sinai Hospital in New York City.