Weight-loss drugs such as semaglutide and tirzepatide have become some of the most talked-about medicines in recent years.
Originally developed to help people with diabetes manage their blood sugar levels, these drugs are now widely used to help people lose weight.
Millions of people around the world have turned to them as obesity rates continue to rise. Now, a large new study suggests these medications may offer another important benefit: they could help lower the risk of certain cancers linked to obesity.
The research, published in the journal Annals of Oncology, examined more than 229,000 adults in the United States who were obese but did not have diabetes. This makes it the first large study to focus specifically on cancer risk among non-diabetic people using these medications for weight management.
Obesity is a major health problem worldwide. It increases the risk of heart disease, stroke, type 2 diabetes, and many types of cancer. Scientists have identified at least 13 cancers that are strongly linked to excess body weight.
These include cancers of the uterus, breast, bowel, kidney, pancreas, thyroid, liver, gallbladder, ovary, stomach, and esophagus, as well as several blood and brain cancers. Together, obesity-related cancers account for a large share of cancer cases in wealthy countries, and rates are rising among younger adults.
Researchers from Houston Methodist Hospital wanted to find out whether weight-loss medications known as GLP-1 receptor agonists could influence this cancer risk. The medications studied included semaglutide, sold under brand names such as Ozempic and Wegovy, and tirzepatide, sold as Mounjaro and Zepbound.
To answer the question, the team analyzed records from a large healthcare database covering more than 113 million patients. They identified 229,467 obese adults without diabetes. About 86,000 of these patients received prescriptions for GLP-1 medications, while about 143,000 received advice on diet and exercise alone.
The average age of participants was 47 years. Researchers carefully matched patients in both groups so the comparison would be as fair as possible. After matching, there were nearly 81,000 people in each group.
The findings were striking. During an average follow-up period of two years, people taking GLP-1 medications had a 41% lower risk of developing obesity-related cancers compared with those who relied on lifestyle changes alone.
The reduction was even greater in certain groups. Among men, cancer risk dropped by nearly 70%. The study also found a 58% reduction in endometrial cancer, a cancer of the uterus that is strongly linked to obesity.
Researchers also noticed differences among racial groups. White patients experienced about a 50% reduction in cancer risk, while a similar reduction was not seen among Black patients.
The researchers said this may be related to differences in healthcare access, underlying health risks, social factors, or biological differences. More research will be needed to understand these findings.
Another important result involved the different medications themselves. Although all GLP-1 drugs appeared to lower cancer risk, tirzepatide showed the largest reduction.
Dr. Aparna Kamat, a gynecologic cancer specialist and senior author of the study, said the findings suggest these medications may have effects that extend far beyond weight loss.
She explained that previous research hinted at lower cancer risks among diabetic patients taking these drugs, but no one had carefully examined their effects in younger, non-diabetic adults who now make up the majority of users.
The researchers believe several factors could explain the results. Losing weight reduces inflammation, lowers hormone changes linked to obesity, improves metabolism, and decreases other biological processes that can encourage cancer growth.
However, scientists do not yet know whether the drugs themselves directly influence cancer development or whether the benefit comes mainly from weight loss.
The authors stress that the study does not prove that GLP-1 drugs prevent cancer. This was an observational study, meaning it looked at existing medical records rather than randomly assigning people to treatment groups. Such studies can identify important links but cannot prove cause and effect.
The relatively short follow-up period is another limitation. Cancer often takes many years to develop, and participants were followed for only about two years. Longer studies will be needed to determine whether the benefits continue over time.
Even with these limitations, the findings are exciting because obesity-related cancers are becoming increasingly common. If future clinical trials confirm these results, weight-loss medications could become an important tool not only for obesity treatment but also for reducing cancer risk.
Overall, the study provides strong evidence that GLP-1 medications may offer health benefits beyond helping people lose weight. The large number of participants adds confidence to the findings. However, the research cannot yet prove that the drugs directly prevent cancer, and longer-term studies are essential.
For now, these medicines should still be prescribed primarily for approved medical reasons such as obesity treatment. Nevertheless, the results suggest that cancer prevention may eventually become an important part of the conversation when doctors and patients discuss these medications.
If you care about cancer, please read studies that a low-carb diet could increase overall cancer risk, and vitamin D supplements could strongly reduce cancer death.
For more information about health, please see recent studies about how drinking milk affects the risks of heart disease and cancer and results showing higher intake of dairy foods linked to higher prostate cancer risk.
Source: Houston Methodist Hospital.
