FAQs About Advanced Breast Cancer Subtypes
After you are diagnosed with breast cancer, your doctor will perform tests to determine the subtype. Subtypes are organized by the presence of specific proteins that help breast cancer cells grow. Doctors will analyze a tissue sample from a biopsy to determine the subtype.
Knowing your breast cancer subtype can help doctors make decisions about treatment. Doctors can recommend treatments that target the specific proteins that are helping your cancer cells grow. For example, some subtypes of breast cancers can be treated by hormone therapies, while others cannot.
What are the main subtypes of advanced breast cancer?
There are 4 main subtypes of breast cancer. They are defined by the presence of certain proteins that promote cancer cell growth. The 4 subtypes are:1
- Luminal A– HR-positive and HER2-negative
- Triple-negative – HR-negative and HER2-negative
- Luminal B – HR-positive and HER2-positive
- HER2-enriched – HR-negative and HER2-positive
HR stands for “hormone receptor.” These are proteins on the surface of some breast cancer cells. Hormones attaching to these receptors fuels the growth of cancer cells.2
HER2 stands for “human epidermal growth factor receptor 2.” Too much of this protein promotes the growth of breast cancer cells.2
How common are each of the subtypes of advanced breast cancer?
The most common subtype of advanced breast cancer is luminal A. Nearly 70 percent of new cases of breast cancer are luminal A. The incidence rate of each subtype in the United States is:1
- Luminal A – 88 new cases per 100,000 women
- Triple-negative – 13 new cases per 100,000 women
- Luminal B – 13 new cases per 100,000 women
- HER2-enriched – 5 new cases per 100,000 women
Combined, the incidence rate of breast cancer is 129 cases per 100,000 women. Experts estimate that there will be more than 280,000 new cases of breast cancer in the United States in 2021.1
Who gets each of the subtypes of advanced breast cancer?
Breast cancer is most common in middle-aged and older women. The distribution of breast cancer subtypes varies depending on age, race, ethnicity, and other factors.1
White women have the highest rate of new cases of luminal A breast cancer. Women with the other 3 subtypes are more likely to be younger, belong to minority groups, and be diagnosed later. For example, Black women have the highest rate of new cases of triple-negative breast cancer.1
What is the outcome for each of the subtypes of breast cancer?
The overall 5-year survival rate for breast cancer is about 90 percent. Breast cancer subtype slightly affects outcome Luminal A cancers have the best outcome. The 5-year survival rate for each subtype is:1
- Luminal A – 95 percent
- Triple-negative – 77 percent
- Luminal B – 90 percent
- HER2-enriched – 84 percent
The stage of cancer at diagnosis affects survival outcome more than the subtype. For example, the 5-year survival rate for all subtypes that have not spread to other parts of the body is above 90 percent. This rate drops to below 45 percent if the cancer has spread to distant body parts.1
What does it mean for breast cancer to be HR-positive or HR-negative?
Some breast cancers use your body’s natural female hormones (estrogen and progesterone) to grow. These breast cancer cells have proteins on their surface called hormone receptors (HRs). HRs catch specific hormones that travel around your body.2,3
Breast cancers that are HR-positive (HR+) have estrogen receptors and/or progesterone receptors. Cells with estrogen receptors use estrogen to grow. Cells with progesterone receptors use progesterone to grow. Breast cancers that are HR-negative (HR-) do not have hormone receptors.2,3
What does it mean for breast cancer to be HER2-positive or HER2-negative?
Changes to the DNA within cancer cells affect how the cancer grows. For example, cancer cells that have too many copies of the HER2 gene make too much of the HER2 protein. These types of breast cancers are called HER2-positive (HER2+). Too much HER2 protein promotes the growth of breast cancer cells.2,3
Breast cancer cells with a normal number of copies of the HER2 gene make a normal amount of HER2 protein. These types of cancers are called HER2-negative (HER2-).2,3
How does the subtype of advanced breast cancer affect treatment?
The subtype of breast cancer helps doctors decide what treatments may be effective. Certain treatments can be more effective depending on your specific HR or HER2 status.3
HR-positive breast cancers may be treated with hormone therapy. This type of treatment blocks hormones from promoting cancer cell growth. Women with luminal A and luminal B breast cancers may benefit from hormone therapy, such as tamoxifen.2,3
HER2-positive breast cancers may be treated with drugs that block the HER2 protein. Women with luminal B and HER2-enriched breast cancers benefit from HER2-targeted treatments, such as Herceptin (trastuzumab).3,4
Women with triple-negative breast cancer cannot be treated with hormone therapy or HER2-specific treatments. Possible treatments for triple-negative breast cancer include:3
- Radiation therapy
- Other non-HER2 treatments
Things to consider
It is important to remember that while statistics reflect trends of an overall group of people with a condition, you are not a statistic. Statistics do not predict your unique situation and what you may experience.
What statistics can do is give you a general idea of how others with a similar course of disease have fared. Your doctor is the best source of information about your specific cancer and the treatment that is right for you.
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