New research is suggesting potential links between GLP-1 drugs and lower risks for some cancers.
The recent findings come as semaglutide becomes more available and as prices drop, with generic versions starting to hit Canadian pharmacies this year.
The new research was presented alongside more than two dozen other studies at the American Society of Clinical Oncology meeting in Chicago, with many finding that patients taking the drugs showed lower risks of developing cancer and disease progression, better survival and improved responses to some treatments compared with people who were not taking the GLP-1s.
Dr. Judith Bray, vice-president of research at the Canadian Cancer Society, said that the research “has the potential to be transformative.”
“These rumbling or smoking guns have been firing off for well over a year now about this possibility,” she said. “So, all of a sudden, the whole research world woke up.”
In one study by the ESMO Annals of Oncology, American researchers examined data on more than 161,000 patients with an average age of 47 who were either obese, did not have diabetes and had not been diagnosed with an obesity-related cancer.
Of these, half used weight-loss injections while the other half were given consultation on diet and exercise, being followed up for two years.
Results found that those who used GLP-1s were significantly less likely to be diagnosed with an obesity-related cancer during the follow-up period, with a reduced risk of 41 per cent.
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Bray also added that previously, “nobody had even thought” of a potential link between GLP-1 drugs and cancer prevention.
Bray added that additional research is needed to see if GLP-1 drugs also contribute to fewer relapses.
From 2022 to 2024, more than two-thirds (68 per cent) of Canadian adults aged 18 to 79 had a body mass index (BMI) classified as overweight or having obesity, an increase from 60 per cent before the COVID-19 pandemic, according to Statistics Canada.
A JCO Oncology Practice study released on June 2 found that “GLP-1 treatment was associated with a lower incidence of breast cancer, independent of age, race, ethnicity, BMI, breast density, and diabetes.”
Conducted between Jan. 1, 2022, and June 30, 2025, more than 110,000 patients between the ages of 45 and 80 who underwent breast imaging were identified. Researchers compared women using GLP-1 medications with women who were not taking these drugs.
Of those women, nearly 14 per cent had been prescribed a GLP-1 drug.
It was found that women using GLP-1 medications showed up to 35 per cent lower risk of developing breast cancer compared to non-users.
To confirm those results, researchers then matched each of more than 15,000 women on a GLP-1 drug with another woman who had a similar background. In this comparison, those taking GLP-1 meds had nearly 31 per cent lower odds of breast cancer.
“While our study was observational and does not definitively confirm an association between GLP-1 medications and reduced breast cancer incidence, it does add to the growing body of evidence suggesting that it’s worth investigating these weight-loss drugs as potential cancer prevention tools,” lead researcher Dr. Elizabeth McDonald said in a press release.
Breast cancer was predicted to be the highest-diagnosed cancer for women in 2026 at 26 per cent by the Canadian Medical Association Journal in April 2026, also sitting amongst the most common causes of cancer-related deaths.
Kimberly Carson, CEO of Breast Cancer Canada, called this research “very encouraging” and hopes “that this is the way in the future.”
“It’s very exciting moving forward and I really love the progress that we’re making here,” she said.
Moving forward, Carson believes that more Canadian research in this area is key.
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