Observational Study of 110,000 Women Finds Association Between GLP-1 Drug Use and 30% Lower Breast Cancer Risk

An analysis of more than 110,000 women ages 45 to 80 found those taking GLP-1 medications were 30% less likely to develop breast cancer, according to a University of Pennsylvania School of Medicine study. Breast cancer accounts for about 30% of all new female cancers annually, with more than 320,000 people expected to be affected this year. The average age range of diagnosis is 45 to 80.

Elizabeth McDonald, professor of Radiology in the University of Pennsylvania Perelman School of Medicine, said the medications were not designed for cancer therapy. “But they do affect many different targets and pathways associated with cancer development, so we’re eager to study them in this context,” she said.

Obesity is linked to 13 types of cancer, including breast, prostate, uterus, pancreas, colon, kidney and liver.

A study published last year found that people on GLP-1 drugs reduced their risk of 10 of the 13 obesity-associated cancers. Previous research found GLP-1 drugs were 41% more effective at preventing obesity-related cancers than bariatric surgery. A separate study of 86,000 adults with obesity found GLP-1 users had a 17% lower cancer risk.

A study examining tirzepatide in mice resulted in about 20% body weight loss and reduced breast cancer tumor size. Tirzepatide is sold as Mounjaro for diabetes and Zepbound for obesity. A trial of more than 17,000 people found semaglutide cut the risk of serious heart attacks and strokes by 20%.

3 million people found GLP-1 users had lower rates of opioid overdose and alcohol intoxication. McDonald said the goal is prevention. “we want to find better options to prevent breast cancer,” she said.