How Different Subtypes of Breast Cancer Are Treated
Before choosing a therapy, doctors need to know what’s fueling the cancer.
One of the ways to categorize breast cancers is by receptor status. Breast cancer cells often have some type of receptor on the surface, and the type of receptor can determine which treatment is used on the breast cancer.
“There are three possible receptors,” says Amy Tiersten, MD, oncologist and hematologist at Dubin Breast Center, Mount Sinai Hospital in New York City. “There are hormone receptors—estrogen and progesterone—and then there’s a protein called HER2.” Learn more about the types of breast cancer here.
Hormone Therapy for Breast Cancer
Breast cancers with estrogen receptors or progesterone receptors are fueled by the respective hormones; these are called hormone receptor-positive breast cancers. For example, when estrogen binds to an estrogen receptor on a breast cancer cell, it helps the breast cancer grow.
Hormone receptor-positive breast cancer is treated with something called hormone therapy, specifically anti-estrogen therapy (even if the breast cancer cells contain progesterone receptors).
“Anti-estrogen medication plays a very big role in the treatment of [hormone receptor-positive] breast cancer, both in preventing a recurrence [and] treating more advanced disease,” says Dr. Tiersten.
Hormone therapy for breast cancer works by preventing estrogen (or progesterone) from binding to the receptor, which helps shrink or eliminate the tumor. Some types of hormone therapy lower the amount of estrogen. Typically, hormone therapy is done after surgery (such as lumpectomy or mastectomy) to eliminate remaining cancer cells throughout the body.
Targeted Therapy for Breast Cancer
Breast cancers with HER2 receptors are fueled by a growth protein called HER2 (or HER2/neu); this is called HER2-positive breast cancer. For this type of breast cancer, the cancer cells contain abnormally high levels of HER2 on the surface.
HER2-positive breast cancer is treated with targeted therapy. This treatment works by targeting the HER2 protein and blocking the growth of cancer cells.
Targeted therapy for HER2-positive breast cancer works so well that “nowadays, it’s considered a good thing to have HER2-positive breast cancer because we have incredibly effective targeted antibodies to that HER2 protein,” says Dr. Tiersten.
Treatment Options for Triple-Negative Breast Cancer
Some types of breast cancer lack all three of the receptors known to fuel breast cancer growth; these cancers are known as triple-negative breast cancers.
Hormone therapy and targeted therapy are newer and more effective types of breast cancer treatment. Unfortunately, these options don’t work on triple-negative breast cancers since they aren’t affected by estrogen, progesterone, or HER2.
“At the time, all we really have for triple-negative breast cancer is your standard, traditional chemotherapy,” says Dr. Tiersten. Luckily, this type of breast cancer is “very sensitive” to chemotherapy, and this treatment is more effective on triple-negative breast cancer than other types of cancer.
Chemotherapy can be done before surgery (neoadjuvant chemotherapy) or after surgery (adjuvant chemotherapy).
Neoadjuvant chemotherapy is used to shrink down a tumor prior to surgery so that “patients are able to become lumpectomy candidates” instead of having to get a full mastectomy, according to Dr. Tiersten.
Adjuvant chemotherapy is used after surgery (lumpectomy or mastectomy) to ensure all residual cancer cells in the body are eliminated.
Learn more about treatment options for triple-negative breast cancer here.
“We really used to consider breast cancer one disease, but biology has moved so far forward that we really tailor the treatment to the specific type of breast cancer,” says Dr. Tiersten.
Dr. Tiersten is a professor of medicine, hematology, and medical oncology at the Icahn School of Medicine at Mount Sinai. She sees patients at the Dubin Breast Center.
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You do have a lump there and
I feel that we should do a biopsy.
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You sure?
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Years ago we thought of
breast cancer as one disease but
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biology has advanced so
much that we now understand that there
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are really different behaving
type of breast cancers.
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And that the presence or absence of the
receptors really determine prognosis and
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treatment and so they're very different
diseases within a breast cancer diagnosis
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There are several different
subtypes of breast cancer, and
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that is dictated by which receptors are on
the surface of the breast cancer cells.
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So there are three possible receptors.
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Receptors, think of them as like little
baseball mitts that sit on the surface of
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the cell.
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There's the estrogen receptor,
the progesterone receptor, and
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then there's a protein called HER2/neu.
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The hormone receptor-positive type,
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the cancers that have those receptors can
respond to anti-estrogen medications.
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The HER2 receptor is a protein
that's overexpressed
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in about 20% of breast cancers, and
it's an important thing to know
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because there are certain targeted
therapies toward the HER2 receptor.
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A triple-negative breast cancer just
means that none of those three receptors
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are present, so
not that it's triply bad, but
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there are three possible receptors
which are absent on those cells.
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Triple-negative breast cancers
are inherently more aggressive,
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they are what's called
poorly differentiated, so
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the cells look very different from normal
breast cells under the microscope.
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Very importantly is they don't have
the option of these incredibly effective
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targeted treatments to the receptor.
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So the big revolution in oncology
is looking at more target or
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biologic treatments.
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And there's a lot of research going
on in triple-negative breast cancer,
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trying to identify other treatments that
are not just cytotoxic chemotherapy.
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Epidemiology, risk factors and the clinical approach to ER/PR negative, HER2-negative (triple-negative) breast cancer. Waltham, MA: UpToDate, 2019. (Accessed on April 9, 2019 at https://www.uptodate.com/contents/epidemiology-risk-factors-and-the-clinical-approach-to-er-pr-negative-her2-negative-triple-negative-breast-cancer.)
Hormone therapy for breast cancer. Atlanta, GA: American Cancer Society, 2017. (Accessed on April 16, 2019 at https://www.cancer.org/cancer/breast-cancer/treatment/hormone-therapy-for-breast-cancer.html.)
Targeted therapy for breast cancer. Atlanta, GA: American Cancer Society, 2018. (Accessed on April 16, 2019 at https://www.cancer.org/cancer/breast-cancer/treatment/targeted-therapy-for-breast-cancer.html.)
Triple negative breast cancer. Dallas, TX: Susan G. Komen, 2019. (Accessed on April 9, 2019 at https://ww5.komen.org/BreastCancer/TripleNegativeBreastCancer.html.)
Triple negative breast cancer. Frisco, TX: National Breast Cancer Foundation, Inc. (Accessed on April 9, 2019 at https://www.nationalbreastcancer.org/triple-negative-breast-cancer.)
What is triple-negative breast cancer? Atlanta, GA: Centers for Disease Control and Prevention. (Accessed on April 9, 2019 at https://www.cdc.gov/cancer/breast/triple-negative.htm.)