Weight-loss injections linked to reduced risk of obesity-related cancer

Weight-loss injections could nearly halve the risk of obesity-related cancer, a new study shows. Cancer experts have called the findings “revolutionary” and could usher in “an entirely new era in preventive cancer medicine.”

Obesity is linked to 13 different types of cancer, The Guardian reports. Although losing weight reduces this risk, scientists have calculated that weight-loss injections have a greater protective effect than simply losing weight.

Researchers in Israel studied 6,000 adults without a history of cancer who had either undergone bariatric surgery or were taking the glucagon-like peptide-1 receptor agonists (GLP-1RAs) liraglutide, exenatide, or dulaglutide. These drugs work by mimicking the body’s production of the hormone GLP-1, which lowers blood sugar levels and helps people feel fuller longer.

Although those who had bariatric surgery lost about twice as much weight as those who took weight-loss drugs, the study, presented at the European Congress on Obesity in Malaga and published in The Lancet's EClinicalMedicine, found that the reduction in cancer risk was generally the same.

According to the researchers, bariatric surgery reduces the risk of developing cancer by 30-42%. Thus, given the relative advantage of surgery in reducing patients' weight, the authors concluded that weight-loss drugs are more effective in preventing obesity-related cancer.

“The protective effects of GLP-1RA against obesity-related cancer are likely due to multiple mechanisms, including reduced inflammation,” said study co-author Israeli professor Dror Diker.

New drugs may prove even more useful, he added. “A new generation of highly potent GLP-1RAs with greater efficacy in reducing weight may provide an even greater benefit in reducing the risk of obesity-related cancers, but further research is needed to ensure that these drugs do not increase the risk of non-obesity-related cancers.”

Commenting on the findings, Professor Mark Lawler, a world-renowned cancer research expert from Queen's University Belfast, said that although it was an observational study and caution was needed when interpreting the results, the results were very interesting.

“We already know that bariatric surgery reduces the risk of obesity-related cancers by about a third; these data suggest that targeting GLP-1 could reduce that risk by nearly 50%, an approach that would revolutionise the prevention of obesity-related cancers. Biologically, this makes sense because targeting GLP-1 reduces inflammation, one of the hallmarks of cancer. While more work is needed on how this works, these data raise the intriguing possibility that injecting GLP-1 could prevent multiple cancers in the general population, including common cancers such as breast and colorectal cancers and hard-to-treat cancers such as pancreatic and ovarian cancers. This work could usher in an entirely new era in cancer preventive medicine.”

Professor Jason Halford, former president of the European Association for the Study of Obesity and head of psychology at the University of Leeds, said the drugs should also be tested in patients with newly diagnosed cancers to see if they improve their chances of survival.

He added that the drugs “could potentially be a new beginning.” And it’s not just prevention, but weight control in people who have recently been diagnosed with cancer is also critical in terms of outcomes. That would be the next thing to look at. More and more cancer cases are being linked to obesity.”

A team of 54 international experts from 12 different countries issued a joint statement at the conference calling for trials of weight-loss drugs to be a priority in cancer prevention. As a result, a team of British scientists, based at the University of Manchester and funded by Cancer Research UK, are planning a large-scale clinical trial involving tens of thousands of patients, which they hope to begin within “three to five years”.

Dr Matthew Harris, from Manchester Cancer Research Centre, said weight loss injections "provide truly fantastic weight loss and could be an intervention that could be delivered on a population scale that we haven't been able to achieve before".