Study: Weight loss drugs can reduce cancer risk by 41%
Medications known to be used for weight loss have been associated with a lower incidence of obesity-related cancers in people without diabetes. The conclusion is from a study published in the scientific journal "Annals of Oncology".
The research analyzed data from 229,467 obese adults without diabetes in the United States and identified that patients treated with drugs from the GLP-1 receptor agonist class - a group that includes semaglutide and tirzepatide, active ingredients in drugs such as Ozempic and Mounjaro - had a significantly lower risk of developing tumors associated with obesity compared to people who only received guidance on diet and physical exercise.
According to the researchers, this is the first investigation to exclusively evaluate the relationship between the use of these medications and the risk of cancer in obese people without diabetes, a population that has been driving the global growth of these weight loss therapies.
How the study was carried out
The researchers used the TriNetX database, which brings together information on approximately 113 million patients in the United States.
Adults with a body mass index (BMI) equal to or greater than 30, without a previous diagnosis of obesity-related cancer and without diabetes were selected. The data analyzed covers the period between December 2014 and June 2025. Of the total participants, 86,422 used GLP-1 class medications to control weight, while 143,045 received only advice on diet or physical exercise.
To reduce possible differences between the groups, the scientists performed statistical matching that resulted in two equivalent populations, each with 80,899 patients.
The average age of participants was 47 years old and follow-up occurred for a median period of two years.
41% reduction in relative risk
After analyzing the data, researchers observed that GLP-1 users had a significantly lower incidence of obesity-related cancers.
The study found a hazard ratio of 0.59. In practice, this means that the group treated with GLP-1 agonists had about a 41% lower relative risk of developing these tumors during the follow-up period when compared to the group that received only lifestyle guidance.
The favorable association was observed in practically all subgroups analyzed, including men, women and people with different degrees of obesity. The results also remained consistent when the researchers applied additional statistical methods to validate the conclusions.
What are cancers associated with obesity
Obesity is considered one of the main risk factors for several types of cancer. Currently, experts recognize at least 13 tumors related to excess body weight, including postmenopausal breast, endometrial, colon and rectum, esophagus, liver, kidney, pancreas, ovarian and thyroid cancers.
With the growth of obesity around the world, doctors and researchers are seeking to understand whether treatments that promote weight loss can also contribute to reducing the risk of these diseases.
GLP-1 agonists were initially developed for the treatment of type 2 diabetes, but have become widely used against obesity due to their ability to reduce appetite, increase the feeling of satiety and promote significant weight loss. Data cited in the study shows that, in the United States alone, the number of obese people without diabetes who used GLP-1 agonists increased from around 21,000 in 2019 to more than 174,000 in 2023.
Semaglutide and tirzepatide
The authors also evaluated the effects of different medications in the class, including semaglutide and tirzepatide, which are currently among the most used treatments for weight loss.
Among the best-known medications are Ozempic and Wegovy, both based on semaglutide and produced by Novo Nordisk. Another medication that has gained prominence recently is Mounjaro, from Eli Lilly. Unlike semaglutide, tirzepatide acts simultaneously on the GLP-1 and GIP hormone receptors, a mechanism that can enhance the effects on weight loss.
The study specifically evaluated users of semaglutide and tirzepatide and found that the association with a lower incidence of obesity-related cancers was observed in both groups.
The results suggest that the observed benefit is not restricted to a single drug, but may be related to the mechanism of action shared by GLP-1 receptor agonists.
What can explain the association
The researchers point to two main hypotheses to explain the results.
The first is the weight loss promoted by the medications. Reducing body fat can reduce chronic inflammatory processes and hormonal changes that favor the development of tumors. The second hypothesis involves a possible direct biological effect of GLP-1 agonists. Previous laboratory studies have indicated that activation of GLP-1 receptors can reduce the proliferation and survival of certain cancer cells.
However, the authors emphasize that it is not yet possible to say which of these mechanisms has the greatest influence nor whether both act simultaneously.
Research does not prove cause and effect
Despite the results considered promising, the researchers themselves highlight that the study does not prove that the drugs prevent cancer.
This is because the analysis was based on real medical records and not a randomized clinical trial, considered the gold standard for establishing cause and effect relationships. Furthermore, the follow-up period was relatively short. Because many cancers take years to develop, experts say prospective studies with longer follow-up will be needed to confirm whether the observed reduction represents a causal effect of the drugs.
"Prospective trials are necessary to confirm causality", highlight the authors in the conclusion.
The authors conclude that the results reinforce the need for specific clinical studies to investigate whether GLP-1 agonists can, in addition to promoting weight loss, contribute to the prevention of obesity-related cancers.
Source: CNN