Science Moves Slowly - But It Moves: What New GLP-1 Research Might Mean for Breast Cancer Prevention

My mom spent 23 years living with breast cancer. In that time, she sat through more appointments than I can count, read stacks of studies she probably didn't need to read, and quietly followed every development in treatment research not always with hope, but always with curiosity. She believed science moved slowly. She also believed it moved. Every step forward mattered to her, even the ones that didn't come in time for her.

So, when something genuinely new turns up in the prevention world, I pay attention.

This past week, something worth talking about came out of one of the biggest cancer research gatherings in the world, the 2026 ASCO Annual Meeting. On June 2nd, a team from the University of Pennsylvania presented findings from a study of more than 110,000 women between the ages of 45 and 80 who were undergoing breast imaging and had a BMI of 25 or higher.” Researchers found that GLP-1 use was associated with roughly a 30% lower incidence of breast cancer.

GLP-1s were built to manage blood sugar for people with type 2 diabetes, then became known more recently for supporting weight loss. What this study suggests is that their reach into the body might extend further than that, into territory researchers are only starting to map.

It helps to understand why that matters. Excess body weight is one of the most well-established, modifiable risk factors for breast cancer, especially after menopause. Fat tissue produces estrogen, and elevated estrogen has long been tied to hormone receptor-positive breast cancers, the most common type. There's also a relationship between insulin resistance, chronic inflammation, and the conditions that let cancer cells take hold. GLP-1 medications affect several of those areas, including weight and metabolic health and researchers are now trying to understand whether those effects, or other biological pathways, might help explain what they observed.”  Some early work is also looking at whether these drugs influence biological pathways tied to cancer development directly, though that piece is still preliminary.

The researchers were careful about how they framed all of this, and it's worth being just as careful here. Dr. Elizabeth McDonald, the study's lead author and a radiology professor at Penn's Abramson Cancer Center, was clear that this is an observational study, it shows an association, not proof that the medication caused the drop in cases. The next step is a prospective randomized trial, which her team is working to get off the ground. That distinction isn't a technicality. It means GLP-1 medications aren't a recommended breast cancer prevention tool today, and this single study isn't a reason for anyone to change what they're doing. It's a reason for scientists to keep digging which is exactly how this kind of progress is supposed to work.

I don't think this changes anything for anyone reading it today. It doesn't replace screening. It doesn't replace screening or the prevention strategies women already discuss with their healthcare providers.  What it does is add one more thread to a body of research that's still being woven, one more reason to believe there might be more tools coming for the women who come after my mom.

Prevention has always been the quieter side of this story. Treatment gets the headlines. Survival gets the awareness campaigns. For the women who never get a diagnosis because something intervened early enough; a screening, a change, a discovery like this one, years down the road, prevention is everything.

My mom would have liked this study.  Not because it would have changed anything for her, but because she believed, all the way through, that every woman who came after her deserved a better set of options than she had.

That belief, her belief, is still what drives everything we do at the World Change Coalition.

Science moves slowly. But it moves.

Holding you in my heart, Mom. Always. Richie

At World Change Coalition, 15% of net proceeds from the purchase of Cathy's Jeans goes directly to nonprofits supporting women in the breast cancer community. Learn more at worldchangecoalition.net.

Note: This article is intended for informational purposes only and should not be considered medical advice. Individuals should consult their healthcare providers before making decisions about medications, screening, cancer prevention, or treatment.