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Drugs that target glucagon-like peptide 1 (GLP-1) have gained lots of attention for their potential health benefits. You may have heard about new weight loss drugs from friends, family, and celebrity influencers. Whether you’re currently treating breast cancer or have completed treatment, you might wonder if these drugs are safe for you.
Continue reading to learn more about GLP-1 drugs and their potential benefits and risks for people currently living with breast cancer and for breast cancer survivors.
GLP-1 drugs are medications used along with diet and healthy lifestyle changes to treat type 2 diabetes (a condition that causes high blood sugar) and obesity.
Glucagon-like peptide-1 is a hormone made in your small intestines, and GLP-1 drugs are synthetic versions made in a laboratory. These medications work by mimicking the hormone’s normal function but may differ slightly in structure, which is why they’re sometimes also called GLP-1 analogs. You may also hear people refer to them as GLP-1 receptor agonists (GLP-1 RAs) or GLP-1 agonists.
The hormone GLP-1 can help lower blood sugar levels in people with type 2 diabetes by triggering a gland called the pancreas to release insulin. The pancreas makes insulin, a hormone that helps your body turn food into energy. Normally, insulin is released when your blood sugar rises after you eat. Insulin lowers your blood sugar by helping the cells in your body use the sugar for energy.
In addition to increasing insulin release, the GLP-1 hormone also:
By mimicking the hormone’s action, GLP-1 drugs can help lower blood sugar and help you lose weight by making you feel more satisfied after eating.
GLP-1 drugs approved by the U.S. Food and Drug Administration (FDA) to treat type 2 diabetes include:
Three GLP-1 drugs are also FDA-approved to treat obesity regardless of whether a person has type 2 diabetes. Obesity is defined as a body mass index (BMI) of 30 or higher. GLP-1 drugs approved for weight loss include:
GLP-1 drugs can help improve health conditions other than diabetes, including high blood pressure, high cholesterol, and fatty liver disease. Because GLP-1 drugs are relatively new, researchers are still learning about their possible role in other health conditions, such as breast cancer. Below are some potential benefits of GLP-1 drugs in people with breast cancer.
It’s important for people with type 2 diabetes to manage blood sugar levels during and after treatment. Some breast cancer treatments, such as hormonal therapy, can increase blood sugar levels and even lead to diabetes.
Your health care team may prescribe a GLP-1 drug as part of your treatment plan to keep your blood sugar in a safe range. Having well-controlled blood sugar may help some cancer treatments work better and reduce your risk of treatment complications.
Obesity is linked to an increased risk of many cancers, including breast cancer. People with obesity also may have worse breast cancer outcomes compared to those without excess body weight. To make matters more complicated, some breast cancer treatments — such as hormonal therapy — can also cause weight gain.
A 2024 study in the Journal of Clinical Oncology reported that GLP-1 drugs helped women with early-stage breast cancer and overweight or obesity achieve significant weight loss. Researchers are still learning if weight loss during and after treatment can help reduce the risk of breast cancer recurrence (when the cancer comes back) or other complications.
In general, weight loss can have many other benefits, including:
Some types of chemotherapy and targeted therapies used to treat breast cancer can cause cardiotoxicity (heart damage). Because GLP-1 drugs can help lower your risk factors for heart disease, researchers have begun to investigate whether these medications can help reduce treatment-related heart damage.
Another 2024 study found that people with breast cancer and type 2 diabetes taking GLP-1 drugs had fewer major cardiovascular problems (conditions related to heart and blood vessels) after receiving cardiotoxic breast cancer treatments such as anthracyclines and HER2 inhibitors, compared to people not taking GLP-1 drugs. However, this is early research, and more studies are needed to confirm these findings in larger and more diverse groups.
A 2023 study found that people with type 2 diabetes taking GLP-1 drugs had a lower risk of colorectal (colon) cancer compared to those taking other diabetes medications. This benefit may be related to the effects of the drug and the weight loss it promotes. However, more research is needed to find out if GLP-1 drugs can prevent other types of cancer, such as breast cancer.
A few early studies suggest that GLP-1 drugs may also help protect against cancer.
In a small study of 20 people with obesity, GLP-1 drugs restored the function of natural killer (NK) cells, a part of the immune system that helps destroy cancer cells. This could be important because people with obesity often have NK cells that don’t work as well.
Early research in animals suggests that GLP-1 drugs may enhance the effectiveness of some immunotherapies. Additionally, a laboratory study found evidence that GLP-1 drugs may slow the growth of lung cancer cells. However, unlike clinical trials, laboratory studies don’t test drugs in humans, so the findings aren’t conclusive.
Research on the effect of GLP-1 drugs on cancer is still in its early stages, but these preliminary results provide researchers with valuable insights into the potential benefits of GLP-1 drugs.
Although GLP-1 drugs can benefit many people, they do come with some risks. We’ll discuss some potential risks of GLP-1 drugs in people with breast cancer below.
Some common adverse effects of GLP-1 drugs are similar to those of chemotherapy side effects, including:
Some people may find it difficult to tolerate the combined side effects of GLP-1 drugs and breast cancer treatments. Talk to your cancer care team about the best way to manage your side effects.
Because they slow digestion, GLP-1 drugs may interact with some medications and make them not work as well. Medications that may be affected by slowed digestion include:
It’s also important to note that some breast cancer treatments can interact with GLP-1 drugs. In one 2024 study, people receiving hormone therapy for breast cancer lost less weight while taking GLP-1 drugs compared to the general population.
Talk to your health care provider about how your medications may interact with GLP-1 drugs.
GLP-1 drugs carry a warning regarding the risk of thyroid cancer. In animal studies, GLP-1 drugs were found to cause thyroid C-cell tumors. It’s unknown whether these drugs have the same effect in humans, but GLP-1 drugs aren’t recommended for people with a family or personal history of thyroid cancer. Talk to your health care provider about your thyroid cancer risk with GLP-1 drugs.
Have a conversation with your oncology team to determine if taking a GLP-1 drug is safe for you, based on your past or current breast cancer treatment plan. It’s important that each member of your health care team is aware of all the drugs and supplements you’re taking. With that information, they can provide the best recommendations for you and help you assess the potential risks and benefits of any treatment option.
MyBCTeam is the social network for people with breast cancer and their loved ones. On MyBCTeam, 73,000 members come together to ask questions, give advice, and share their stories with others who understand life with breast cancer.
Have you taken a GLP-1 drug? Did it help you lose weight or better control your blood sugar? What side effects did you experience? Share your thoughts in the comments below, or start a conversation by posting on your Activities page.
Maybell Nieves, M.D.
graduated from Central University of Venezuela, where she completed medical school and general surgery training.
Learn more about her here.
Amanda Jacot, Pharm.D
earned a Bachelor of Science in biology from the University of Texas at Austin in 2009 and a Doctor of Pharmacy from the University of Texas College of Pharmacy in 2014.
Learn more about her here.
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