Weight Loss Drugs & Cancer Risk: What To Know
- GLP-1 receptor agonists (GLP-1 RAs), such as semaglutide (sold under brand names Ozempic and Wegovy) and tirzepatide (Zepbound), have shown unprecedented results for individuals with obesity, often helping them shed 10% to 20% of their body weight.
- Because obesity and obesity-related conditions have been linked to several types of cancer, doctors believe that these medications may also be able to help some patients lower their cancer risk.
- Carrying excess weight can lead to chronic inflammation and hormonal changes that promote the growth of certain cancers.
- GLP-1 RAs work by mimicking a hormone your body naturally makes (called glucagon-like peptide-1) that helps regulate blood sugar and feelings of hunger.
Because obesity and obesity-related conditions have been linked to several types of cancer, doctors believe that these medications may also be able to help some patients lower their cancer risk.
Read MoreWhy Obesity Matters for Cancer Risk
The World Health Organization and other major health agencies have identified obesity as a risk factor for multiple cancers, including breast (in postmenopausal women), colorectal, liver, and pancreatic cancer, among others. In fact, the International Agency for Research on Cancer (IARC) points to 13 “obesity-related cancers,” covering a wide range of body systems.Carrying excess weight can lead to chronic inflammation and hormonal changes that promote the growth of certain cancers. Therefore, weight loss — through lifestyle adjustments, surgery, or medications — might help reduce the likelihood of developing these cancers over time.
How GLP-1 Receptor Agonists Work
GLP-1 RAs mimic a hormone your body naturally makes (called glucagon-like peptide-1) that helps regulate blood sugar and feelings of hunger. Initially developed to treat type 2 diabetes by lowering blood sugar levels, these medications were later found to have an impressive effect on appetite control. As a result, many people who take them lose significant amounts of weight.
“GLP-1 … is a hormone that is secreted in the L cells of the intestines, and we all make GLP-1 after we start to eat a meal,” Dr. Lofton explains. “After food reaches the stomach, the stomach sends GLP-1 to the brain to sense hunger is no longer present and the person starts to feel more full. In the hypothalamus, specifically of the brain, once the brain receives that GLP-1, it sends a message to the person to stop eating.”
The native GLP-1 that our bodies make and the GLP-1 agonists go to the brain and block appetite signals, go to the stomach to help it empty more slowly, and help shrink fat cells, Dr. Lofton explains.
And weight reduction is not the only effect these medications may have. Researchers are learning that GLP-1 RAs could also influence other behaviors — such as smoking or alcohol use — and possibly reduce certain health risks that come with obesity. In fact, several large studies show that people taking GLP-1 RAs have better heart health, lower rates of kidney problems, and may even be less likely to develop some types of cancer.
Recent Studies on Cancer Risk
Comparison With No Treatment
A study presented at the 2024 ASCO Annual Meeting indicated that people with obesity who received GLP-1 RAs had a notably lower risk of developing certain obesity-related cancers compared with those who received no weight loss intervention.
Another retrospective study found that GLP-1 RAs may reduce the risk of 10 of the 13 most common obesity-associated cancers — such as pancreatic, liver, and ovarian cancer — when compared with insulin therapy in patients with type 2 diabetes.
Comparison With Bariatric Surgery
Bariatric surgery (weight loss surgery) has a well-documented track record of lowering cancer risk. For example, one study revealed a 32% reduction in obesity-related cancers 10 years after surgery compared to people who did not have surgery.
New data suggest that while bariatric surgery typically leads to greater short-term weight loss than GLP-1 RAs, people who use GLP-1 RAs may still lower their cancer risk similarly to those who have surgery. Interestingly, in one large database study, patients on GLP-1 medications even had a slightly lower overall risk of dying (from any cause) than those who underwent surgery — although both approaches showed substantial health benefits.
Comparison With Metformin
Metformin is a common first-line medication for type 2 diabetes, and previous research has hinted that metformin might reduce certain cancer risks. However, when GLP-1 RAs were compared directly to metformin, they did not show a clear additional cancer-prevention benefit except for a possible trend toward fewer colorectal and gallbladder cancers — though the differences were not statistically significant.
One study also found a slightly higher risk of kidney cancer among those on GLP-1 RAs compared to metformin alone, but these results need further confirmation.
Long-Term Use: Why It Matters
One challenge with GLP-1 RAs is that their benefits can fade quickly if the medication is stopped. Unlike bariatric surgery, which creates lasting changes in the digestive tract, GLP-1 drugs need to be taken long-term to maintain their effects. Once a person discontinues them, the body no longer receives that constant boost of hunger-suppressing signals, and weight regain can happen quickly.
Regaining weight after stopping treatment may undo some of the possible benefits related to lowering cancer risk. There are also important considerations about changes in body composition when people lose weight quickly (often losing muscle along with fat), and whether repeated cycles of weight loss and regain could affect overall health.
Side Effects and Concerns
GLP-1 RAs are generally considered safe, but like all medications, they come with potential side effects.
These can include:
- Nausea, vomiting, diarrhea, or constipation
- Stomach discomfort or reflux
- Possible increased risk of gallstones due to rapid weight loss
- Rare concerns about thyroid cancer (though large studies have shown conflicting results and no definitive increase in thyroid cancer risk)
“The most commonly reported side effects with GLP-1 agonists tend to be gastrointestinal in nature because this is a gastrointestinal hormone. What’s commonly reported is nausea and patients tend to have more side effects the first time they take medication, and it tends to decline as they take that same dose again,” Dr. Lofton explains, adding that measures can often be taken to help mitigate side effects.
If you’re considering a GLP-1 medication, talk with your doctor about these risks and how to manage or reduce them. It’s also important to keep in mind that these drugs can be expensive, and insurance coverage varies widely. High costs often make it difficult for patients to stay on treatment over the long haul, which is exactly when these medications seem to provide the most benefits.
For GLP-1 RAs to have a meaningful impact on cancer reduction or any other obesity-related complication, patients need reliable access to them. Many insurance plans do not fully cover the cost, and the out-of-pocket price can be thousands of dollars per year. Researchers and clinicians worry that if the financial barriers are not lowered, the benefits of these “game-changing” drugs might remain out of reach for many.
Should You Consider a GLP-1 RA?
Deciding on a weight loss approach — whether it’s lifestyle modifications, medication, or surgery — is highly personal. Some points to consider with your healthcare team include:
- Your Overall Health: Do you have type 2 diabetes or other chronic conditions affected by weight? GLP-1 RAs can improve blood sugar control and lower cardiovascular risks, in addition to promoting weight loss.
- Cancer Risks: If you have a strong family history or other risk factors for obesity-related cancers, long-term medication use might offer extra benefits — but the evidence, while promising, is still growing.
- Commitment and Cost: These medications often need to be taken indefinitely to maintain weight loss. Make sure you feel comfortable with the potential side effects, follow-up visits, and ongoing costs.
- Alternatives: Bariatric surgery, structured lifestyle changes, and other treatments may also reduce cancer risk and help you lose weight. Talk with your doctor about which option is best suited to your overall health and personal goals.
Bottom Line
GLP-1 receptor agonists are powerful tools in the fight against obesity. Emerging research suggests they may also help reduce the risk of certain cancers that are tied to excess weight, potentially to a degree that mirrors — or, in some aspects, surpasses — bariatric surgery. However, questions remain about long-term adherence, muscle loss, side effects, and whether the benefits persist after stopping the medication.
If you’re considering a GLP-1 RA, it’s crucial to have a thorough discussion with your healthcare provider about the benefits, risks, and costs of treatment. Together, you can map out a plan that helps you achieve healthier weight control, lowers your risk for certain obesity-related cancers, and enhances your overall well-being for the long run.
Questions To Ask Your Doctor
- Am I a candidate for a GLP-1 receptor agonist?
- How will I be monitored if I start taking these drugs?
- What lifestyle changes should I make while taking these drugs?
- What if I need to stop taking the medication?
Learn more about SurvivorNet's rigorous medical review process.
