Is There Medication to Prevent Breast Cancer?

Key TakeawaysEngland has approved a drug for breast cancer prevention—one that is also available in the U.S.There are two main types of medications used to help prevent breast cancer in higher-risk patients: SERMs and AIs. These drugs work slightly differently but all help stop cancer cells from developingExperts say it’s still important for people to go for regular breast cancer screenings and understand their individual risk based on factors such as family history.

Key Takeaways

England has approved a drug for breast cancer prevention—one that is also available in the U.S.There are two main types of medications used to help prevent breast cancer in higher-risk patients: SERMs and AIs. These drugs work slightly differently but all help stop cancer cells from developingExperts say it’s still important for people to go for regular breast cancer screenings and understand their individual risk based on factors such as family history.

England recentlymade headlinesfor approving the drug anastrozole for breast cancer prevention in women with an increased risk of developing the disease.

The NHS said in a press release that while not all eligible candidates will choose to take the medication, it is estimated that if 25% do opt to take the drug, around 2,000 cases of breast cancer could potentially be prevented in the country.

While the news is celebrated in England, anastrozole has been used for both breast cancer treatment and prevention in the U.S. for many years. In fact, there are several drugs available for breast cancer prevention.

Here’s what you need to know about which drugs are available, how they work, and who is eligible.

Tamoxifen

What It’s Approved For

Tamoxifen belongs to a group of drugs called selective estrogen receptor modulators, orSERMs. These drugs can act as estrogen in the body or block against estrogen, depending on the target tissue.

Why It Helps Prevent Breast Cancer

“Tamoxifen is what we generally call an estrogen receptor blocker,”Nina D’Abreo, MD, director of medical oncology of the Perlmutter Cancer Center at NYU Langone Hospital, Brooklyn, told Verywell.

How Effective Is It?

Clinical trials have found that tamoxifen can significantly reduce the likelihood of developing breast cancer.

The preventative effects last beyond the time a patient is on the medication, D’Abreo said, explaining that the reduced risk is long-lasting.

“The thing to remember is that you take the pills for five years, but this really is lifetime protection—it’s not just for the time you’re on the medication,” she said.

Who Is Eligible

The FDA has approved tamoxifen for patients with estrogen-positive breast cancer and people with a higher risk of developing the disease.Both premenopausal and postmenopausal patients are eligible to take this drug.

This high-risk group may include people with a family history of breast cancer, a history oflobular carcinoma in situ, a history ofatypical ductal hyperplasia (ADH)oratypical lobular hyperplasia (ALH)or a gene mutation linked to an increased chance of breast cancer, such as theBRCA mutation.

Patients can use an online tool to estimate their breast cancer risk throughThe Gail Model.

“Most of the studies [on breast cancer drugs] included women with a five-year risk of greater than 1.66 per cent based on The Gail model,” D’Abreo said.

It’s important to note, however, that The Gail Model does not accurately estimate breast cancer risk for patients with the BRCA1 or BRCA2 gene or a history of invasive or in situ breast cancer. There are also other factors the model cannot account for, so it’s crucial people speak to their healthcare provider to understand individual circumstances and prevention options.

How Do You Take It and What Are the Side Effects?

Tamoxifen is typically taken daily for five years for breast cancer prevention. It is available in both pill and liquid form.

D’Abreo said the side effects of tamoxifen tend to be well-managed and mild for most patients and can include hot flashes, weight gain, and vaginal dryness.

There are possible more serious side effects, like blood clots, uterine cancer, and stroke, but these tend to be very rare.

How Younger Women Can Access Mammograms

Raloxifene

It is not used as a treatment for breast cancer.

Raloxifene, like tamoxifen, is also a SERM.“Raloxifene has only been studied in postmenopausal women, but it has a similar sort of mechanism as tamoxifen as it is an estrogen receptor blocker,” D’Abreo said.

Tamoxifen, on the other hand, showed about a 50% reduction rate over this period.

“The way it was studied initially was for prevention of bone loss,”Katherine Tkaczuk, MD, director of the Breast Evaluation and Treatment Program at the University of Maryland Greenebaum Comprehensive Cancer Center and a professor of medicine at the University of Maryland School of Medicine, told Verywell. “This drug is for older, postmenopausal women.”

A person using raloxifene for breast cancer prevention would need to be at a higher risk of developing the disease. These factors can include a family history of breast cancer or certain biopsy results, “such as finding lobular carcinoma in situ, atypical ductal hyperplasia or atypical lobular hyperplasia,” Tkaczuk said.

“If someone has these findings on their biopsy, this would automatically put them at higher risk,” she added.

Raloxifene is an oral medication and it is taken daily, often for five years.

Common side effects include hot flashes, flu-like symptoms, abdominal pain, chest pain, joint pain, leg cramps, swelling of the legs and feet, cough, shortness of breath, and sweating.

Clinical trials found that the most serious adverse reaction related to the drug was venous thromboembolism (blood clotting in a vein).

D’Abreo said raloxifene has been used for a long time to treat osteoporosis, and that serious side effects, like blood clots, are very rare.

Anastrozole

Anastrozole belongs to a class of drugs calledaromatase inhibitors(AIs).

“Aromatase inhibitors work differently than SERMs, and they have also been used in the United States for [breast cancer treatment] for many years now,” D’Abreo said.

Anastrozole, which is sold under the brand name Arimidex, is FDA-approved for treatment of hormone receptor-positive breast cancer in postmenopausal patients.But it is also often used off-label for breast cancer prevention.

Another AI shown to help prevent breast cancer is exemestane (Aromasin).This drug is currently approved for the treatment of breast cancer but might be used off-label for prevention as well.

In premenopausal patients, estrogen is produced mainly in the ovaries. It is also produced in peripheral tissues such as the breasts, liver, brain, skin, bone, and pancreas, though to a lesser degree.

But in patients who have gone throughmenopause, their ovaries are no longer making much estrogen, so peripheral tissues are the predominant source of the hormone.

Research on AIs shows about a 50% lifetime reduction risk of breast cancer when taken for five years, D’Abreo said.

It’s important to remember, however, that breast cancer prevention drugs are not for all types of breast cancer.

“Whether it’s SERM or an AI, such as anastrozole, they really only have been shown to prevent estrogen-positive breast cancer,” Tkaczuk said.

“They don’t really have much effect on certain more rare subtypes of breast cancer, such astriple-negative breast cancer.”

If the drug is used for breast cancer prevention, ideal candidates would be patients with higher risk of developing breast cancer.

Like with the SERMs, high-risk factors can include a history of breast cancer in the family, abnormal breast cell growth or biopsy results, and an elevated score of breast cancer risk onThe Gail Model.

The side effects of AIs are similar to menopause, D’Abreo said. They can include hot flashes, joint stiffness, vaginal dryness, insomnia and hair thinning.

“The side effect that’s most important for us is the bone loss that happens—osteopeniaorosteoporosis,” D’Abreo said.

Research shows that female patients taking an AI are at a two- and four-fold increased risk of bone loss compared to females in the general population.This differs from a SERM like raloxifene which helpspreventbone loss.

“If you have bone loss already from natural menopause, these AIs can increase the risk of bone loss while you’re on the pill,” D’Abreo said.

The Importance of Screening

While breast cancer prevention medications are incredibly helpful in reducing the likelihood of developing the disease, experts say regular screenings—including check-ups and mammograms—are vital. Speaking with your healthcare provider about your breast cancer risk can help prevent disease or disease progression.

“Even if you don’t have a biopsy that shows one of the high-risk findings, speak to your [healthcare provider] to see whether you would be somebody who could be considered a higher risk for breast cancer,” D’Abreo said.

What This Means For YouEngland recently made headlines for approving the drug anastrozole for breast cancer prevention in women with an increased risk of developing the disease. The drug has been used for breast cancer prevention in the U.S. for years, and is one of several available medications.

What This Means For You

England recently made headlines for approving the drug anastrozole for breast cancer prevention in women with an increased risk of developing the disease. The drug has been used for breast cancer prevention in the U.S. for years, and is one of several available medications.

12 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.An KC.Selective estrogen receptor modulators.Asian Spine J. 2016;10(4):787-791. doi:10.4184/asj.2016.10.4.787National Cancer Institute.Tamoxifen citrate.Vogel VG, Costantino JP, Wickerham DL, et al.Effects of tamoxifen vs raloxifene on the risk of developing invasive breast cancer and other disease outcomes: the NSABP Study of Tamoxifen and Raloxifene (STAR) P-2 trial.JAMA. 2006;295(23):2727-2741. doi:10.1001/jama.295.23.joc60074National Cancer Institute.Hormone therapy for breast cancer.American Cancer Society.Deciding whether to use medicine to reduce breast cancer risk.National Library of Medicine: DailyMed.Evista—raloxifene hydrochloride tablet[drug label].American Cancer Society.Tamoxifen and raloxifene for lowering breast cancer risk.National Cancer Institute.The study of tamoxifen and raloxifene (STAR): questions and answers.Arimidex.Highlights of prescribing information.National Cancer Institute.Exemestane reduces breast cancer risk in high-risk postmenopausal women.Mount Sinai.Menopause.Hadji P, Aapro MS, Body JJ, et al.Management of aromatase inhibitor-associated bone loss (AIBL) in postmenopausal women with hormone sensitive breast cancer: joint position statement of the IOF, CABS, ECTS, IEG, ESCEO IMS, and SIOG.J Bone Oncol. 2017;7:1-12. doi:10.1016/j.jbo.2017.03.001

12 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.An KC.Selective estrogen receptor modulators.Asian Spine J. 2016;10(4):787-791. doi:10.4184/asj.2016.10.4.787National Cancer Institute.Tamoxifen citrate.Vogel VG, Costantino JP, Wickerham DL, et al.Effects of tamoxifen vs raloxifene on the risk of developing invasive breast cancer and other disease outcomes: the NSABP Study of Tamoxifen and Raloxifene (STAR) P-2 trial.JAMA. 2006;295(23):2727-2741. doi:10.1001/jama.295.23.joc60074National Cancer Institute.Hormone therapy for breast cancer.American Cancer Society.Deciding whether to use medicine to reduce breast cancer risk.National Library of Medicine: DailyMed.Evista—raloxifene hydrochloride tablet[drug label].American Cancer Society.Tamoxifen and raloxifene for lowering breast cancer risk.National Cancer Institute.The study of tamoxifen and raloxifene (STAR): questions and answers.Arimidex.Highlights of prescribing information.National Cancer Institute.Exemestane reduces breast cancer risk in high-risk postmenopausal women.Mount Sinai.Menopause.Hadji P, Aapro MS, Body JJ, et al.Management of aromatase inhibitor-associated bone loss (AIBL) in postmenopausal women with hormone sensitive breast cancer: joint position statement of the IOF, CABS, ECTS, IEG, ESCEO IMS, and SIOG.J Bone Oncol. 2017;7:1-12. doi:10.1016/j.jbo.2017.03.001

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

An KC.Selective estrogen receptor modulators.Asian Spine J. 2016;10(4):787-791. doi:10.4184/asj.2016.10.4.787National Cancer Institute.Tamoxifen citrate.Vogel VG, Costantino JP, Wickerham DL, et al.Effects of tamoxifen vs raloxifene on the risk of developing invasive breast cancer and other disease outcomes: the NSABP Study of Tamoxifen and Raloxifene (STAR) P-2 trial.JAMA. 2006;295(23):2727-2741. doi:10.1001/jama.295.23.joc60074National Cancer Institute.Hormone therapy for breast cancer.American Cancer Society.Deciding whether to use medicine to reduce breast cancer risk.National Library of Medicine: DailyMed.Evista—raloxifene hydrochloride tablet[drug label].American Cancer Society.Tamoxifen and raloxifene for lowering breast cancer risk.National Cancer Institute.The study of tamoxifen and raloxifene (STAR): questions and answers.Arimidex.Highlights of prescribing information.National Cancer Institute.Exemestane reduces breast cancer risk in high-risk postmenopausal women.Mount Sinai.Menopause.Hadji P, Aapro MS, Body JJ, et al.Management of aromatase inhibitor-associated bone loss (AIBL) in postmenopausal women with hormone sensitive breast cancer: joint position statement of the IOF, CABS, ECTS, IEG, ESCEO IMS, and SIOG.J Bone Oncol. 2017;7:1-12. doi:10.1016/j.jbo.2017.03.001

An KC.Selective estrogen receptor modulators.Asian Spine J. 2016;10(4):787-791. doi:10.4184/asj.2016.10.4.787

National Cancer Institute.Tamoxifen citrate.

Vogel VG, Costantino JP, Wickerham DL, et al.Effects of tamoxifen vs raloxifene on the risk of developing invasive breast cancer and other disease outcomes: the NSABP Study of Tamoxifen and Raloxifene (STAR) P-2 trial.JAMA. 2006;295(23):2727-2741. doi:10.1001/jama.295.23.joc60074

National Cancer Institute.Hormone therapy for breast cancer.

American Cancer Society.Deciding whether to use medicine to reduce breast cancer risk.

National Library of Medicine: DailyMed.Evista—raloxifene hydrochloride tablet[drug label].

American Cancer Society.Tamoxifen and raloxifene for lowering breast cancer risk.

National Cancer Institute.The study of tamoxifen and raloxifene (STAR): questions and answers.

Arimidex.Highlights of prescribing information.

National Cancer Institute.Exemestane reduces breast cancer risk in high-risk postmenopausal women.

Mount Sinai.Menopause.

Hadji P, Aapro MS, Body JJ, et al.Management of aromatase inhibitor-associated bone loss (AIBL) in postmenopausal women with hormone sensitive breast cancer: joint position statement of the IOF, CABS, ECTS, IEG, ESCEO IMS, and SIOG.J Bone Oncol. 2017;7:1-12. doi:10.1016/j.jbo.2017.03.001

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