Could “weight-loss shots” do more than help with weight loss — and potentially lower breast cancer risk?

At this year’s Annual Meeting of the American Society of Clinical Oncology (ASCO), more than ten studies pointed to a direction worth watching: GLP-1 receptor agonists, such as Mounjaro, may be associated with lower rates of cancer incidence, recurrence, or metastasis across a range of cancers — including some that are not clearly linked to obesity.

Many people think GLP-1 drugs are a recent development. In fact, this class of medications was first approved for diabetes treatment in 2005 and began to be used for obesity treatment in 2014.

GLP-1 drugs do more than support weight loss. They can also lower blood glucose, improve insulin resistance, and reduce chronic inflammation. High blood glucose, insulin resistance, and chronic inflammation are all factors that may influence the development and progression of cancer.

One study presented this year, involving patients with stage I to stage III cancer, found that compared with patients taking DPP-4 inhibitors, those taking GLP-1 medications had a lower risk of developing distant metastases across several types of solid tumors. The study also suggested that GLP-1 may influence the tumor immune environment and inhibit cancer cell proliferation.

Another study, involving more than 110,000 women, found that under comparable conditions, women taking GLP-1 medications had an approximately 30% lower rate of breast cancer diagnosis.

But there is an important distinction to make:

Being associated with a lower risk of cancer does not mean that GLP-1 drugs have been proven to prevent or treat cancer.

Most of the evidence available today still comes from retrospective or observational studies, and GLP-1 drugs have not been approved as cancer-prevention medications. Longer-term and more rigorous clinical trials are still needed to establish a true causal relationship.

What is truly worth watching is not that we have suddenly discovered a “cancer-prevention weight-loss shot,” but that we are beginning to see a potentially deeper connection between metabolism, inflammation, and cancer than previously understood.

Losing weight may be one of the most visible effects of GLP-1. How these drugs may reshape the body’s underlying disease environment could be the more important question for the next stage of research.