- Four new observational studies to be presented at ASCO suggest GLP-1 drugs like Ozempic and Mounjaro reduce tumor progression, lower overall mortality, and decrease the risk of developing breast cancer.
- A Cleveland Clinic study of more than 10,000 early-stage cancer patients found lung cancer progression rates were cut roughly in half among GLP-1 users — 10% vs. 22% — with similar reductions in breast, colorectal, and liver cancers.
- An MD Anderson analysis found over 95% of GLP-1 users with breast cancer were alive after five years, compared with 89.5% for non-users; a UPenn study found GLP-1 users were about 25% less likely to be diagnosed with breast cancer at all.
- The findings are observational, not from randomized controlled trials, meaning causality is not yet established — but researchers say the consistency of the signal across hundreds of thousands of patients in multiple databases is difficult to ignore.
What Happened?
A suite of four new studies — to be presented at the American Society of Clinical Oncology annual meeting — links GLP-1 receptor agonist drugs, including Novo Nordisk’s Ozempic and Eli Lilly’s Mounjaro, to meaningfully better cancer outcomes. The most striking data comes from the Cleveland Clinic, which tracked over 10,000 patients with early-stage cancers. Compared to patients on other diabetes medications, those on GLP-1s saw lung cancer progression rates drop from 22% to 10%, and breast cancer progression rates drop from 20% to 10%. Colorectal and liver cancers showed similar patterns. Separately, UT MD Anderson found a 5.5-percentage-point improvement in five-year survival for breast cancer patients on GLP-1s, and the University of Pennsylvania found a 25% reduction in the likelihood of being diagnosed with breast cancer among GLP-1 users.
Why It Matters?
GLP-1 drugs are already the most commercially valuable pharmaceutical class in history, approved for weight loss, diabetes, cardiovascular risk reduction, and sleep apnea. If their anti-tumor properties are confirmed in randomized controlled trials, the implications for both oncology and the economics of these drugs would be enormous. The mechanism is not yet understood — it could be indirect, driven by metabolic improvements and weight loss independently associated with lower cancer risk, or it could be direct, as GLP-1 receptors have been identified on the surface of some tumor cells. Notably, neither Novo Nordisk nor Eli Lilly is currently running cancer-specific trials for these drugs, leaving a significant research gap despite the commercial incentive to close it.
What’s Next?
Researchers are calling for randomized controlled trials — the gold standard for establishing causality — to determine whether the cancer benefit is real and attributable to the drugs themselves or to confounding variables like better healthcare access among GLP-1 users. The ASCO presentation will put these findings in front of the oncology community for the first time, likely sparking debate and accelerating calls for prospective studies. Watch for whether Novo Nordisk or Eli Lilly announces cancer-related research programs in the months ahead, and whether payers or regulators begin factoring potential cancer benefits into coverage decisions.
Source: The Wall Street Journal
