Weight-loss drugs like Wegovy may help stave off some cancers

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Drugs like Ozempic, Wegovy and Zepbound have transformed treatment for obesity and diabetes. Now researchers are excited about their potential impact on other conditions, including addiction and sleep apnea — and even cancer.

Scientists see this class of drugs, called GLP-1 agonists, as a breakthrough because of how they act on the brain to regulate the body’s hormones, slow digestion, and tamp down hunger. And in several recent studies, they show early promise in preventing many common cancers — including breast, colon, liver, and ovarian — known to be driven by obesity and excess weight.

“It's a hopeful story, which is, frankly, what people need,” says Arif Kamal, an oncologist specializing in breast cancer as well as chief patient officer at the American Cancer Society.

Though research on GLP-1 drugs is still in its relative infancy, so far studies fairly consistently show their benefit in staving off certain cancers. One research letter published in JAMA Oncology last year, for example, suggests GLP-1 drugs might reduce the risk of colon cancer, even among people who are not overweight. A more recent analysis in JAMA Network Open suggests GLP-1s provide far more protection against cancer for diabetic patients than insulin treatments.

Another recent study presented at the American Society of Clinical Oncologists meeting in June, showed both bariatric surgery and GLP-1 medications dramatically reduce the risk of the 13 obesity-related cancers. Among those who had bariatric surgery, that risk declined by 22% over 10 years compared to those who received no treatment. But among those taking GLP1 medications, risk dropped by a whopping 39%.

“And I think a 39% risk reduction is one of the most impactful risk reductions we've ever really seen,” says Kamal.

GLP-1 agonist drugs were originally developed to treat diabetes nearly two decades ago. Over the past decade, regulators started approving them as treatments for weight loss – first as liraglutide, sold under the brand Saxenda and, more recently, in the form of semaglutide or tirzepatide, under brands like Wegovy and Zepbound.

When it comes to cancer prevention, scientists are finding the link between obesity in cancer is complex and intertwined; the obesity-related cancers are heavily concentrated among organs involved in digestion and metabolism, like the liver and pancreas, for example, as well as among gynecologic cancers, including breast and uterus. Reproductive organs are highly sensitive to the hormone estrogen, which plays a role in allowing cells to grow rapidly during pregnancy, for example.

But Kamal says there’s also an especially close relationship between estrogen and cancer. “What we do know is that estrogen in particular — and possibly some other hormones, but estrogen for sure — drives the growth of many cancers,” he says. And fat cells increase production of estrogen.

That means women today are increasingly susceptible to cancer. Historically, men faced a much higher risk of developing cancers — in large part because they were more likely to engage in high-risk behaviors like smoking or drinking, Kamal says. But in recent years, the high prevalence of obesity among both men and women is closing that gender gap.

Obesity is also likely the most significant driver behind increasing cancer rates among younger adults, he says, just as tobacco was in generations past.

“Unhealthy weight is the smoking of our generation,” Kamal says.

That’s why indications that GLP-1 drugs may help slash that risk is so significant.

What’s more, that ASCO study suggests that GLP-1 drugs have a notable impact on cancer risk, even when patients don’t lose a lot of weight as a result of taking them. In other words, the medications seem to act on a number of the body’s mechanisms to reduce vulnerabilities to cancer.

“We think the protective effects of GLP-1s are probably multifactorial,” says Cindy Lin, resident physician at Case Western Reserve and co-author of the June ASCO study. “Part of it is weight [loss], but other factors may be contributing as well — better glycemic controls, anti-inflammatory effects.”

More research is necessary and inevitable — especially studies looking at the newer weight-loss formulations of GLP-1 medications, says Benjamin Liu, another resident physician at Case Western and co-author of the ASCO study.

He says he’s encouraged by the data so far. “It's very exciting to have, especially since it's more of a noninvasive strategy compared to bariatric surgery, and a lot more patients will be open to it.”