Medications like semaglutide and tirzepatide have grown significantly in popularity in the last few years. Part of a group of prescription drugs called glucagon-like peptide 1 (GLP-1) agonists, these medications can be prescribed for weight loss, to help people with type 2 diabetes manage their blood sugar levels or both.
Research has produced mixed findings on links between these drugs and cancer. Some research suggests a link between GLP-1 drugs and thyroid cancer. While more recent research concludes that drugs that help people lose weight may prevent several obesity-associated cancers (AOC).
A recent study using lab animals found a possible link between certain GLP-1 drugs and higher risk of thyroid tumors. But according to Sasan Fazeli, M.D., clinical director of the Thyroid and Endocrine Cancer Clinic at City of Hope® Cancer Center Duarte, these findings are still inconclusive.
“These are just correlations, not causation,” Dr. Fazeli explains, adding that “a couple of other studies have since come out, including one published in The BMJ and they didn’t show any correlation, so the full picture has yet to be discovered.”
For now, Dr. Fazeli’s recommendation is that people who have a family history of medullary thyroid cancer should consult a thyroid specialist or endocrinologist if they are considering GLP-1 medications. Those who have been treated for medullary thyroid cancer but still have signs of the disease should likely avoid these medications.
However, the benefits these drugs offer in terms of managing obesity may outweigh any possible risks. Obesity is not only a known risk factor for cancer, but it may also make some cancer treatments less effective.
This article covers the basics on GLP-1 medications and what we know about their relationship to cancer, including:
- What are GLP-1 medications?
- Can semaglutide cause cancer?
- Does tirzepatide cause cancer?
- Can GLP-1 drugs help curb cancer risk?
If you’ve been diagnosed with cancer and are interested in a second opinion on your diagnosis and treatment plan, call us or chat online with a member of our team.
What are GLP-1 medications?
GLP-1 medications can help people with type 2 diabetes manage their blood sugar levels and weight. There are multiple GLP-1 medications available. This list includes the most common brand names and the medication they contain:
- Semaglutide (Ozempic®, Wegovy®, Rybelsus®)
- Tirzepatide (Mounjaro®, Zepbound®)
- Dulaglutide (Trulicity®)
- Exenatide (Byetta®, Bydureon®)
- Liraglutide (Victoza®, Saxenda®)
In most cases, GLP-1 drugs are taken via injection, though some come in pill form. A medication like semaglutide works by causing the body to produce more insulin, the hormone that helps control blood sugar levels.
Sometimes, GLP-1s are prescribed to help people with obesity lose weight and reduce their risk of health issues. Scientists aren’t yet sure how these drugs contribute to weight loss. However, they do slow down the body’s digestion process, which might curb hunger.
Can semaglutide cause cancer?
There is no evidence of a direct link between semaglutide and cancer. However, some studies have suggested a correlation between using semaglutide and a greater risk of developing a certain kind of medullary thyroid cancer, the rarest of the four types of thyroid cancer, affecting only about 1,000 people every year.
“About 95 percent of medullary cancers come from the C cells, which are regular thyroid cells that make the thyroid hormone,” explains Dr. Fazeli. “There is no known connection between GLP-1 drugs and these cancers. The potential risk is only for 4 to 5 percent of medullary thyroid cancers that develop in a different cell group.”
Put simply, this means that any possible correlation between taking semaglutide and thyroid cancer would affect fewer than 50 people per year. And Dr. Fazeli stresses that other studies have found that taking semaglutide does not increase the risk of thyroid tumors at all.
“I would only tell a patient to stop taking semaglutide if they had medullary thyroid cancer and only until we finalize the status of the patient as far as disease progression,” says Dr. Fazeli. “I would not tell them to stop if they were getting benefit out of semaglutide.”
Does tirzepatide cause cancer?
Tirzepatide is another common medication used in GLP-1 medications. There is mixed evidence as to whether there is any link between tirzepatide and thyroid cancer risk.
Some research suggests that tirzepatide and other GLP-1 drugs may increase the likelihood of tumors but notes that these medications have significant other health benefits.
Other studies have found that taking tirzepatide reduced the risk of breast cancer in lab animals, most likely due to helping manage the effects of obesity.
Can GLP-1 drugs help curb cancer risk?
While GLP-1 drugs do not directly reduce cancer risk, they may help people manage obesity.
“Obesity has been connected to many cancers, including thyroid,” says Dr. Fazeli. “What I see is that obese people get worse inflammation or their immune system is weaker or their cancer is more aggressive.”
Obesity has been linked to an increased risk of 13 cancers. And researchers at Case Western Reserve University School of Medicine, Cleveland, Ohio, suggest that using GLP-1 drugs to lose wight may reduce the risk of 10 of those, including:
- Colorectal cancer
- Esophageal cancer
- Endometrial cancer
- Gallbladder cancer
- Kidney cancer
- Liver cancer
- Ovarian cancer
- Pancreatic cancer
- Meningioma
- Multiple myeloma
“These findings provide preliminary evidence of the potential benefit of GLP-1s for cancer prevention in high-risk populations and support further preclinical and clinical studies for the prevention of certain OACs,” researchers say.
This is why it is important to understand the risks and benefits of taking GLP-1 drugs.
“The prognoses for most thyroid cancers are very good,” Dr. Fazeli says. “Patients with obesity are going to get diseases other than cancer, so it may make sense that they try to lose weight, improve their immune system, their lifestyle and their life expectancy.”
Given that GLP-1 medications have shown benefits in terms of heart health and dietary wellness, the best approach for any patient is to talk to a thyroid specialist, endocrinologist or their cancer doctor before deciding whether they should consider these drugs.
“People need to seek expert opinion to understand if the benefits make these drugs a viable and beneficial option for them,” says Dr. Fazeli.
If you’ve been diagnosed with cancer and are interested in a second opinion on your diagnosis and treatment plan, call us or chat online with a member of our team.
