Weight loss jabs like Wegovy ‘DON’T increase cancer risk’, major study finds
DIABETES jab Ozempic and the weight-loss drug Wegovy have soared in popularity in recent months.
But there has been concern that the class of drugs - called (GLP-1 RA) - might increase the risk of thyroid cancer.
Now, a major new study by the Karolinska Institutet has found no evidence of such a link, deeming that GLP-1 drugs don't increase people's risk of developing the cancer.
Widely used to treat conditions like diabetes and obesity, the jabs work by mimicking the GLP-1 hormone produced naturally by your gut when you eat food, to control blood sugar levels, slow down digestion of food and reduce hunger pangs.
Despite their relatively recent spike in popularity, the drugs have already been the subject of much research.
Earlier studies and adverse event data suggested that GLP-1 drugs could be associated with an increased risk of thyroid tumours.
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But scientists weren't able to draw clear conclusions due to limitations in their data and methodology, meaning this potential side effect was surrounded in uncertainty.
“Many people take these medicines, so it is important to study potential risks associated with them,” noted Björn Pasternak, principal researcher at the Department of Medicine, Solna, at Karolinska Institutet in Sweden.
“Our study covers a broad group of patients and provides strong support that GLP-1 analogues are not associated with an increased risk of thyroid cancer.”
Researchers analysed national register data from Denmark, Norway, and Sweden of about 145,000 patients treated with GLP-1 analogues, mainly liraglutide or semaglutide, and 290,000 patients treated with another diabetes medication, .
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These are a class of oral diabetes drugs, also known as gliptins, that help regulate blood glucose levels by protecting a group of gastrointestinal hormones called incretins from damage.
Meanwhile, semaglutide is the active ingredient in both Ozempic and Wegovy, while liraglutide is the main ingredient of weight loss jab Saxenda.
Scientists analysed each group's risk of developing thyroid cancer over the course of just under four years.
Their results, published to the British Medical Journal, showed that GLP-1 treatments were not associated with an increased risk of thyroid cancer.
The results were consistent also when compared to a third diabetes medication group, SGLT2 inhibitors.
“We cannot rule out that the risk of certain subtypes of thyroid cancer is increased in smaller patient groups that we could not study here, for example in people with a high congenital risk of medullary thyroid cancer who are advised against using these drugs,” Peter Ueda, assistant professor at the Department of Medicine, added.
Thyroid cancer is affects the small butterfly-shaped gland that sits in the front, lower part of your neck and makes hormones.
It's quite rare in the UK, with around 3,900 Brits diagnosed with it each year, says.
It causes symptoms like:
- A lump in your neck
- A hoarse voice that lasts for more than 3 weeks
- A sore throat or difficulty swallowing that does not get better
Harnessing weight loss jabs for other conditions
The Karolinska Institutet is running an ongoing research programme to investigate the effects and potential side effects of newer diabetes medications such as GLP-1 analogues and SGLT2 inhibitors.
These medications are now being used to treat broader patient groups, including those with obesity, heart failure, and kidney failure.
A recent French study even suggested that GLP-1 drugs could be used to slow the progression of Parkinson's disease.
Dr Pasternak said: “We know from randomised clinical trials that they have positive effects, but clinical reality is different with patients varying in disease severity, comorbidities, and adherence to treatment recommendations.
“It’s therefore essential to investigate how these medicines perform in everyday clinical settings.”
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Research shows that GLP-1 drugs could be harnessed to improve health in other ways, as they appear to have potential to treat Alzheimer's, as well as heart disease, fatty liver disease, and chronic kidney disease.
It's been suggested that patients with sleep apnoea, heart failure and alcohol addiction could also benefit.
Everything you need to know about drugs like Ozempic
HERE'S what you should know about Ozempic, Wegovy, Saxenda and Mounjaro.
Weight loss jabs are a hot media topic at the moment, with hundreds of success stories sharing how they helped them shed the pounds.
In March 2023, the NHS announced it would make Wegovy, a drug made by Danish firm Novo Nordisk, available on prescription to thousands of obese Brits.
It contains the drug semaglutide, which is said to have helped reality star Kim Kardashian and Twitter boss Elon Musk lose weight.
Wegovy, which helped a third of people reduce their weight by 20 per cent in trials, is now available from pharmacies like Boots.
How do they work?
The jabs work by suppressing your appetite, making you eat less calories and therefore lose weight.
To do this, an ingredient found in the fat-busting drug, known as Semaglutide, mimics the role of a natural hormone, called GLP-1.
GLP-1 is part of the signalling pathway that tells your body you have eaten, and prepares it to use the energy that comes from your food.
London GP and founder of , Dr Zoe Watson, said: “Your body naturally produces an appetite regulating hormone called glucagon-like peptide-1.
“These jabs work by regulating your appetite, which can lead to eating fewer calories and losing weight.”
Aren’t they diabetes drugs?
Semaglutide, the active drug in Wegovy, was originally sold under the name Ozempic specifically for diabetes patients.
But they started noticing it helped suppress their appetites, stopping them eating as much and helping them shed the pounds.
So Novo Nordisk developed Wegovy, which contains the same chemical but at higher doses specifically to aid weight loss.
Wegovy is not prescribed for diabetes patients.
Can I get them?
Wegovy is offered on prescription to obese adults given specialist weight loss treatment.
The NHS currently also offers a similar drug called Saxenda, or liraglutide.
Both are only available on Tier 3 and Tier 4 weight management services, which means you have to be referred to weight management clinics led by experts.
GPs can’t prescribe them on their own either, Dr Watson said.
The jabs have to be taken as part of an overall programme to help with lifestyle changes and psychological support to get the best effect from the medication prescribed.
But despite being approved for use, supply of Wegovy on the NHS has been postponed indefinitely because of a surge in worldwide demand.
Supply was also halved in the US because of the skyrocketing demand.
Are there any risks?
Like all medicines, the jabs do not come without side effects.
Around half of people taking the drug experience gut issues, including sickness, bloating, acid reflux, constipation and diarrhoea.
Dr Sarah Jarvis, GP and clinical consultant at patient.info, said: “One of the more uncommon side effects is severe acute pancreatitis, which is extremely painful and happens to one in 500 people.”
Other uncommon side effects include altered taste, kidney problems, allergic reactions, thyroid tumours, gallbladder problems and hypoglycemia.
What other options are there?
Mounjaro (brand name for tirzepatide) also came onto the market in early 2024.
Like Wegovy, tirzepatide stems from a drug originally designed to treat diabetes.
The weekly injection helped overweight people drop more than two stone in 18 months.
It is available with to order with a prescription online from pharmacies including Superdrug and LloydsPharmacy Online Doctor.
It works in a similar way to Wegovy and Saxenda, but is more effective.
Dr Mitra Dutt from says: “Based on clinical trials, 96 per cent of people were able to lose more than five per cent of their body fat using Mounjaro. In similar trials, 84 per cent of people lost more than five per cent of their body weight on Wegovy, and 60 per cent on Saxenda.
“Mounjaro works by activating two hormonal receptors (GIP and GLP-1), which enhance insulin production, improve insulin sensitivity, and work to decrease food intake."