Despite earlier excitement regarding GLP-1 drugs like Ozempic and Zepbound and their potential connection to reducing the risk of obesity-related cancers, recent findings are pouring some cold water on that fire. According to research published in the Annals of Internal Medicine, these medications "probably have little or no effect" on lowering the risk for such cancers. Dr. Cho-Han Chiang, previously engaged in the study as an internal medicine resident at Mount Auburn Hospital and now a medical oncology fellow at the Northwell Health Cancer Institute, has highlighted the counterintuitive nature of these findings given GLP-1’s role in weight loss and the established link between obesity and cancer risk.
What initially fueled the hopes were studies like one from 2024, cited by NBC Chicago, indicating that Type 2 diabetes patients on GLP-1 medication had significantly lower risks of 10 obesity-related cancers. However, Chiang stressed that these were observations from existing patient data, not findings from a controlled trial, leaving room to question whether patients on GLP-1 treatments were healthier to begin with. To thoroughly test the initial hypothesis, Chiang's team reviewed 48 randomized controlled trials with a substantial sample size of 94,245 patients but observed no significant impact on cancer risk over a median follow-up of 70 weeks.
The study, while methodical, isn't without its limitations. One major point highlighted is that the trials analyzed were not initially designed to measure cancer outcomes. Dr. Kandace McGuire, chief of breast surgery at the Massey Comprehensive Cancer Center, who was not involved in the research, suggested that the inconclusive results might be an artifact of the studies' designs rather than a definitive answer on GLP-1's cancer impact. Echoing McGuire, Dr. Susan Wolver, who directs the Medical Weight Loss Program at VCU Health, mentioned in a NBC News report that despite the drugs' recent approval for weight loss, their long-term effects remain largely unknown.
Among the concerns with any medication is the potential for unintended side effects, and GLP-1 drugs bear a boxed warning about a rare form of thyroid cancer based on past animal studies. While Chiang acknowledged the persistence of such associations, the human data still present a mixed bag, making it difficult to definitively determine the cancer risk. Deputy director of the O'Neal Comprehensive Cancer Center at the University of Alabama at Birmingham, Dr. Bassel El-Rayes, found the recent research reassuring but alluded to the necessity for long-term studies to truly grasp the drugs' effects. "The patients who are using the drugs at this moment are safer than what we thought before this paper came out," El-Rayes told NBC News, not failing to highlight that many questions remain unanswered.
For now, physicians and patients alike are to navigate the space between the potential benefits and unknowns of GLP-1 drugs. While they may not substantially reduce cancer risk or metastases, at least according to current evidence, their positive effects on conditions like diabetes and heart failure still make them a valuable tool in the medical arsenal for treating obesity and its related complications. As further data surfaces and follow-up periods extend, a clearer picture of GLP-1 drugs and their relationship with cancer will inevitably come into focus.
