In a landmark study of 229,000 obese Americans without diabetes, researchers have discovered that weight loss drugs are reshaping cancer prevention in ways no one anticipated. GLP-1 receptor agonists—medications like semaglutide and tirzepatide that have become household names in recent years—reduced the risk of obesity-related cancers by 41% over an average two-year follow-up period, according to research published in Annals of Oncology.
The finding matters because it reveals a secondary benefit of drugs already transforming obesity treatment. When these medications were initially developed to treat diabetes, few imagined their cancer-prevention potential. But the population taking them has changed dramatically. GLP-1 RA use among obese, non-diabetic adults in the US skyrocketed from approximately 21,000 patients in 2019 to more than 174,000 in 2023—meaning the majority of users today are younger patients seeking weight management, not diabetes control.
The research team, led by Dr. Aparna Kamat, director of the Division of Gynecologic Oncology at Houston Methodist Hospital, analyzed data from a nationwide database covering 113 million US patients. Between December 2014 and June 2025, they tracked 86,422 patients who received GLP-1 RA prescriptions alongside 143,045 patients who relied on diet and exercise alone. After carefully matching the groups to create fair comparisons, the researchers identified powerful patterns. Men who took these drugs saw their obesity-related cancer risk plummet by nearly 70%—substantially steeper than the overall reduction. Among gynecologic cancers specifically, endometrial cancer risk dropped 58%, a particularly significant decrease given that endometrial cancer is one of the malignancies most tightly linked to excess body weight.
The 13 cancers linked to obesity—including endometrial, breast, bowel, kidney, pancreatic, thyroid, ovarian, esophageal, gastric, liver, gallbladder cancers, plus multiple myeloma and meningioma—account for roughly 40% of all cancers diagnosed in high-income countries. Their incidence is rising rapidly among younger adults, making prevention strategies crucial.
The study also revealed important variations by race and medication type. Among white patients, obesity-related cancer risk reduction was about 50%, though this benefit did not materialize among Black patients studied—a disparity the researchers attributed to factors including differential access to care, varying risk profiles, and biological differences. When comparing different GLP-1 formulations, all reduced cancer incidence, but tirzepatide users experienced the greatest reduction.
"We already had evidence suggesting these drugs might reduce cancer risk in diabetic patients," Dr. Kamat explained, "but most people now taking GLP-1 RAs for weight loss do not have diabetes. They are younger obese patients and represent a completely different population. No one had studied this before."
The average age of participants was 47 years, underscoring how these medications are increasingly being used by middle-aged adults as a weight management tool. This work represents the first investigation of GLP-1 RAs and obesity-related cancer incidence in non-diabetic obese populations—a crucial gap in our understanding. As these drugs continue reshaping obesity treatment across the country, their potential to prevent cancer may prove equally transformative.