Can I use GLP-1 medications if I have cancer or am a cancer survivor?

Dr Michelle King unpacks when a cancer survivor is eligible to take GLP-1 medications.

GLP-1 agonists are currently all the rage. These include medications, such as semaglutide, tirzepatide, and liraglutide that have been widely popularised by celebrities for their weight loss benefits.

They were originally developed for people with Type 2 diabetes and later for management of obesity. These medications help balance blood glucose by stimulating insulin secretion and suppressing glucagon secretion; are cardiorenal protective; and anti-inflammatory.

Their weight loss benefit comes from delaying gastric emptying, so you feel fuller for longer. They work on two hormones: ghrelin and leptin; these hormones are related to hunger and satiety. The one that effects hunger, ghrelin, is easy to remember, as it’s the one that makes your stomach growl.

At therapeutic dosages, many patients were shown to lose up to 20% of their body weight^.1,2,3

The downside is the gastrointestinal side effects, such as nausea, vomiting, and diarrhoea. In addition, because they delay gastric emptying, they can have a negative effect on anaesthetic outcomes when going in for surgery.

The other negative is that, for many people struggling with obesity, when you stop the medication, you can regain the weight you lost. Lifestyle modification is essential for long-term weight management, as well as the potential long-term use of GLP-1 medication.

Who should not use this medication?

When this medication first came out, there was a lot of concern that there was an increased risk of pancreatic cancer and medullary thyroid cancer associated with their use. Later studies have failed to show that this was true.⁴ A recent study published in Lancet, 2025 showed that there was no overall increase in risk of cancer related to GLP-1 use.⁵

However, if you have a diagnosis of pancreatic cancer, you should avoid using the drug because of the increased risk of pancreatitis.

Secondly, it’s generally advised to avoid GLP-agonist medication while in active treatment as it can worsen nausea and vomiting and affect the absorption of oral chemotherapeutics.

In addition, with rapid weight loss, you lose muscle mass too, which, if you are receiving chemotherapy, can result in increased side effects.

What about survivorship?

Obesity and high body fat can contribute to the recurrence of certain cancers, such as colon, rectum, gastric, hepatocellular, gallbladder, pancreatic, kidney, oesophageal, meningioma, thyroid, endometrial, ovarian, and post-menopausal breast cancer. With the higher your body mass index (BMI) is, the greater your risk.⁴ So, losing weight will reduce the risk of recurrence.

Additionally, studies are showing that the GLP-1 agonists may decrease the risk of certain types of cancer which are related to obesity (colorectal and hepatocellular cancer).⁴

Who qualifies for treatment?

Many people lose weight during active cancer treatment, so if your BMI is normal, you would not be a candidate for treatment.

However, if you are obese (BMI greater than 30) or have a BMI greater than 27 and one comorbid condition, such as Type 2 diabetes, hypertension, or high cholesterol, you would qualify for treatment. Unfortunately, despite their health benefits, medical aids do not pay for GLP-1 agonists, so you would have to pay out of pocket.

References

1. Wojtara M, Mazumder A, Syeda Y, Mozgała N. Glucagon‐like Peptide‐1 receptor agonists for chronic weight management. Advances in Medicine. 2023;2023(1):9946924.
2. Sarma S, Palcu P. Weight loss between glucagon‐like peptide‐1 receptor agonists and bariatric surgery in adults with obesity: a systematic review and meta‐analysis. Obesity. 2022;30(11):2111-21.
3. Wharton S, Aronne LJ, Stefanski A, Alfaris NF, Ciudin A, Yokote K, et al. Orforglipron, an oral small-molecule GLP-1 receptor agonist for obesity treatment. N Engl J Med. 2025;393(18):1796-806.
4. Valencia-Rincón E, Rai R, Chandra V, Wellberg EA. GLP-1 receptor agonists and cancer: current clinical evidence and translational opportunities for preclinical research. The Journal of Clinical Investigation. 2025;135(21).
5. Gamborg M, Grand MK, Grell K, Rosthøj S, Pedersen-Bjergaard U, Torp-Pedersen C, et al. Long-term cancer risk in users of GLP-1 agonists in Denmark: a nationwide emulated trial. The Lancet Regional Health–Europe. 2025;55.

Dr Michelle King is a psychiatrist with a special interest in chronic pain and palliative care. She is dedicated to improving quality of life for patients through compassionate, evidence-based approaches. She currently serves as President of the Pain Society of South Africa (PAINSA).

Visit michellekingpsychiatrist.com

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