ACS Research Highlights

Can Ozempic & Mounjaro Reduce the Risk of Colorectal Cancer?

Early study finds GLP-1 medicines reduce the risk of colorectal cancer more than other diabetes medicines, especially for people with overweight/obesity.

The Challenge

People with overweight or obesity may have a higher risk of developing colorectal cancer as well as 12 other types of cancer compared to people without those conditions. 

People with type 2 diabetes may also have an increased risk of developing colorectal cancer. And, the risk of developing type 2 diabetes may be higher for people who have obesity or overweight.

People may assume that losing weight could reduce the risk of developing both conditions. However, research on whether losing weight might lower the risk of developing cancer—including colorectal cancer—is limited. (Evidence is growing that intentional weight loss may lower the risk of developing breast cancer after menopause and endometrial cancer.)

There is, however, evidence that losing weight may lower the risk of developing type 2 diabetes. For people already diagnosed with type 2 diabetes, there’s evidence that losing weight may help reduce complications from the condition.

According to the American Diabetes Association (ADA) Standards of Care in Diabetes, 2024: “There is strong and consistent evidence that obesity management can delay the progression from prediabetes to type 2 diabetes and is highly beneficial in treating type 2 diabetes.”

Currently, there’s a newer class of medicines, known as GLP-1s, that are getting a lot of media attention because they are used to treat type 2 diabetes, and some are also approved for weight loss.

Not surprisingly, some researchers are asking—could the GLP-1s used to treat type 2 diabetes and overweight/obesity one day be used to lower the risk of developing colorectal cancer?

Popular GLP-1 Medicines 

Also known as GLP-1 receptor agonists or GLP-1Ras, the acronym GLP-1 stands for glucagon-like peptide-1. Most people are more familiar with one of the often more popular brand names. Some of these are approved for treating people with type 2 diabetes, overweight/obesity, or both.

Approved for Type 2 Diabetes (weight loss may occur as a side effect)

  • Adlyxin
  • Bydureon
  • Byetta
  • Mounjaro (a GLP-1/GIP receptor agonist)
  • Ozempic
  • Rybelsus
  • Trulicity
  • Victoza

Approved for Overweight/Obesity

  • Saxenda
  • Wegovy
  • Zepbound

The Research

Rong Xu, PhD, recently published a research letter in JAMA Oncology that described a study partially funded by a grant from the American Cancer Society (ACS). The study was based on the hypothesis that GLP-1s would reduce the risk of developing colorectal cancer better than other diabetes medicines.

Xu co-led the study and worked with fellow researchers from Case Western Reserve School of Medicine and The MetroHealth System in Cleveland. They used a special platform to analyze the electronic health records of more than 1 million patients from 59 health care organizations across 50 states. In that group, over 7 million had type 2 diabetes.

They honed the study group to just over 1.2 million patients with type 2 diabetes and without a diagnosis of colorectal cancer. They studied the group for 15 years—from 2005 to 2019. During that period, patients were prescribed a diabetes medication for the first time.

The researchers compared the use of GLP-1s with 7 types of diabetes treatments. They also analyzed people with overweight/obesity and those without either condition.

Findings for People with Type 2 Diabetes and without Obesity/Overweight

GLP-1s were associated with a decreased risk of developing colorectal cancer compared with most types of other diabetes medicines in people with type 2 diabetes and without obesity/overweight. Specifically, the group taking a GLP-1 had a lower incidence of colorectal cancer than those in groups taking insulin, metformin, SGLT2 inhibitors, sulfonylureas, or thiazolidinediones.

  • GLP-1s vs Insulin. Among the 22,572 people with diabetes and without obesity/overweight who received insulin, the researchers identified 167 cases of colorectal cancer. Among the 22,572 matched people treated with GLP-1, they identified only 94 cases of colorectal cancer. That represents a 44% decreased incidence of colorectal cancer for those who took a GLP-1 medicine compared to those who took insulin to treat type 2 diabetes without obesity/overweight.

  • GLP-1s vs Metformin. In a similar comparison, the researchers found a 25% decreased incidence of colorectal cancer for people with type 2 diabetes and without obesity/overweight who took a GLP-1 medicine vs those taking metformin to treat type 2 diabetes without obesity/overweight.

GLP-1s were associated with a lower—but not statistically significant—risk for colorectal cancer compared with alpha-glucosidase and DPP-4 inhibitors thiazolidinediones in people with type 2 diabetes and without obesity/overweight.

Findings for People with Type 2 Diabetes and with Obesity/Overweight

GLP-1s were associated with a lower risk for colorectal cancer compared with all types of diabetes medicines.

  • GLP-1s vs Insulin. Among the 9,398 people with type 2 diabetes and overweight/obesity who received insulin, the researchers identified 67 cases of colorectal cancer. Among the 9,398 matched people treated with GLP-1, they identified 35 cases of colorectal cancer. That represents a 50% decreased incidence of colorectal cancer for those who took a GLP-1 medicine compared to those taking insulin.

  • GLP-1s vs Metformin. In a similar comparison, the researchers found a 42% decreased incidence of colorectal cancer for those taking a GLP-1 medicine compared to those who took metformin.

Their findings were consistent between men and women. 

Both the group of people with overweight/obesity and without it had fewer cases of colorectal cancer in people who received a GLP-1 medicine compared with one of the other diabetes medicines. But we found more profound effects in the group of people with obesity/overweight and type 2 diabetes. This suggests that GLP-1 medicines have a potential protective effect against colorectal cancer, which may be partly due to losing weight and partly due to other mechanisms not related to weight loss.”

Rong Xu, PhD

Center for AI in Drug Discovery and Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine

Former American Cancer Society Grantee

“To our knowledge, this is the first study about this class of popular weight loss and diabetes drugs to show a reduced incidence of colorectal cancer compared with other antidiabetic drugs,” Xu added.

What does ‘matched people’ mean?

To accurately compare the drugs’ effects, the researchers matched patients between cohorts based on:

  • Adverse socioeconomic determinants of health (housing and economic circumstance, upbringing, education, physical environment, social environment)
  • Demographics
  • Family and personal history of cancer and polyps in the colon
  • Family circumstance
  • Lifestyle factors (exercise, diet, smoking, and alcohol drinking)
  • Preexisting conditions (overweight, obesity, ulcerative colitis, or cystic fibrosis)
  • Procedures received (bariatric surgery, colonoscopy, and radiation therapy)

Why It Matters

Large retrospective population research like this observational study can find correlations but cannot prove causations. That is, this study doesn’t prove that taking GLP-1s reduces the risk of developing colorectal cancer risk, but its findings warrant further investigation with clinical trials.

This exciting data also paves the way for additional studies including testing whether GLP-1s reduce the risk of other types of cancer associated with obesity.