Does Semaglutide Cause Cancer?

Every medication has the potential for unwanted effects. These might include interactions with other medications, minor side effects, or serious long-term health consequences. Semaglutide — a treatment for diabetes and weight loss — is no exception.

You may have heard that semaglutide (Wegovy, Ozempic, Rybelsus) might raise the risk of cancer. There’s even an FDA boxed warning about its possible link to a rare type of thyroid tumor. But how big is this risk? And does semaglutide increase the risk of any other types of cancer? Here’s what you need to know.

Which cancers are semaglutide associated with?

Two types of cancer have been studied in connection with semaglutide: a specific type of thyroid cancer and pancreatic cancer. So far, the data doesn’t show a cause-and-effect relationship. In other words, semaglutide doesn’t cause thyroid or pancreatic cancer based on available studies. 

But these cancer types are very rare. So, it may be too soon to find a relationship. Ongoing research may provide more answers in the future.

Thyroid cancer

Semaglutide has a black box warning about a possible link to a rare thyroid cancer called medullary thyroid cancer (MTC). You may also see this called a C-cell tumor. This warning isn’t specific to semaglutide. Other medications in this same class, called glucagon-like peptide-1 receptor agonists (GLP-1 RAs), have the same warning.

The thyroid gland, located in your neck, makes and releases certain hormones that are important to many functions in your body. There are four types of thyroid cancer, and medullary thyroid cancer is the rarest. It happens when the hormone-producing C cells grow out of control. This is the type linked to GLP-1 RAs.

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This link between semaglutide and C-cell tumors was discovered during safety studies in rodents that were given semaglutide. But researchers haven’t seen the same effect in humans. Follow-up studies suggest that MCT happens in fewer than 1% of people, meaning the risk seems to be very low. 

The largest review of semaglutide, which included tens of thousands of people, found no increased risk of any type of cancer. Researchers rated the evidence for this conclusion as high quality.

Pancreatic cancer

Medications like semaglutide affect different parts of your digestive system. This includes your pancreas, the organ near your stomach that releases insulin. 

Some older GLP-1 medications — like exenatide (Byetta) and sitagliptin (Januvia) — were once thought to increase the risk of pancreatitis and pancreatic cancer. Because of this, researchers looked into whether semaglutide carried the same risk.

But so far, large studies haven’t been able to find a link to pancreatitis or pancreatic cancer. One study found no increased cancer risk in people taking GLP-1 medications for diabetes. Another review found similar results when looking at people taking semaglutide for all indications, including weight loss. Both the FDA and the European Medicines Agency have also come to the same conclusion. 

How does semaglutide affect potential cancer risk?

Many cells in your body have GLP-1 receptors, so medications like semaglutide can affect many different organs. Rodents, in particular, have more GLP-1 receptors in their thyroid cells. When activated, these receptors kick off a cascade that leads to C-cell overgrowth. This might explain the increased cancer rates seen in rodents given semaglutide. 

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• How does weight impact your cancer risk? Research shows that certain types of cancer are more common in people with a higher weight. 

• Does Ozempic cause gallbladder issues? It might increase your risk of gallstones and gallbladder infections — but this risk is still relatively small.

• How long do you need to take Wegovy? Most people need to take Wegovy for the long term to maintain weight loss.

As for your pancreas, semaglutide increases the number of beta cells in your pancreas. These cells secrete insulin, which helps control blood sugar levels. This effect is one reason this medication helps people with diabetes. 

But even though semaglutide can increase growth of certain cells, researchers are still trying to understand semaglutide and its effects better. For now, there’s not enough information to know if or how it affects cancer risk in humans.

Can semaglutide help prevent any types of cancer?

It’s possible. Some types of cancer are more likely in people with excess body weight. Experts aren’t exactly sure why. They’re testing different theories, including whether losing extra body weight could also lower cancer risk.

A recent study supports this theory. Researchers found that people with body mass index of 35 or higher who took GLP-1 RAs had a 39% lower risk of weight-related cancers than those who didn’t take them. Interestingly, people who had bariatric surgery had only a 22% lower risk, even though they lost more weight. This could suggest that GLP-1 RA treatment might lower cancer risk in ways beyond just weight loss.

Of course, it’s still too early to say if semaglutide or similar medications can prevent cancer. But expect more to come in this area. 

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Written by:

Mandy Armitage, MD

Mandy Armitage, MD, has combined her interests in clinical medicine with her passion for education and content development for many years. She served as medical director for the health technology companies HealthLoop (now Get Well) and Doximity.

Edited by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

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