News Release

Weight-loss surgery cuts risk of developing colorectal cancer by more than a third

Meeting Announcement

American Society for Metabolic and Bariatric Surgery

DALLAS – June 7, 2022 – People who had weight-loss surgery were 37% less likely to develop colorectal cancer compared to individuals with obesity who did not have the surgery, according to a new study* presented here today at the American Society for Metabolic and Bariatric Surgery (ASMBS) Annual Meeting (#ASMBS2022). 

The American Cancer Society estimates that this year more than 150,000 people will be diagnosed with colorectal cancer, the third leading cause of cancer-related deaths in the United States. Having obesity or overweight increases the risk for many types of cancer including colorectal cancer, as well as other life threatening diseases and conditions including type 2 diabetes, heart disease and stroke.

In a metaanalysis, researchers from the Military Institution of Aviation Medicine in Warsaw, Poland, Texas Tech School of Medicine in El Paso and the Mayo Clinic College of Medicine in Rochester, MN examined data from 13 previous studies on weight-loss surgery and colorectal cancer that followed more than 3.2 million patients for up to 10 years. The included studies were published between 2008 and 2021, which researchers say covers a longer and more up-to-date period than previous systematic reviews on the subject. 

“Bariatric surgery may offer significant protection against colorectal cancer in individuals with obesity that extends at least 10 years, the length of follow-up in several of the studies we analyzed,” said study co-author Michal Janik, MD, a general and bariatric surgeon at the Military Institution of Aviation Medicine. “This is an important finding because colorectal cancer takes time to develop and even over decade the protective effect is still there.” 

The study did not account for risk factors other than obesity and did not measure weight loss or correlate findings to any particular method of weight-loss surgery. Researchers say future studies should take into account the difference in the incidence of colorectal cancer among the different types of bariatric surgery and in patients with different durations of obesity.

“This study shows that when you treat obesity with weight-loss surgery, you may also be preventing colorectal cancer at the same time, not to mention a whole host of other diseases and conditions that are improved, resolved or prevented,” said Shanu Kothari, MD, President, ASMBS, who was not involved in the study. 

About Weight-Loss Surgery

Metabolic/bariatric or weight-loss surgery such as gastric bypass and sleeve gastrectomy have been shown to be the most effective and long-lasting treatment for severe obesity. The operations improve or resolve diseases including type 2 diabetes, heart disease and high blood pressure and leads to significant and durable weight loss. Its safety profile is comparable to some of the safest and most commonly performed surgeries in the U.S., including gallbladder surgery, appendectomy and knee replacement. Weight-loss surgery is generally reserved for people with severe obesity, which means about 75 to 100 pounds overweight or having a BMI of 35 or higher with an obesity-related disease. Obesity is linked to early death and more than 40 diseases including type 2 diabetes, hypertension, heart disease, stroke, osteoarthritis and at least 13 different types of cancer.[i],[ii],[iii] According to the ASMBS, less than 1% of those eligible for weight-loss surgery currently have it in any given year -- about 256,000 bariatric surgeries were performed in 2019, the latest estimates available. 


The ASMBS is the largest organization for bariatric surgeons in the nation. It is a non-profit organization that works to advance the art and science of bariatric surgery and is committed to educating medical professionals and the lay public about bariatric surgery as an option for the treatment of severe obesity, as well as the associated risks and benefits. It encourages its members to investigate and discover new advances in bariatric surgery, while maintaining a steady exchange of experiences and ideas that may lead to improved surgical outcomes for patients with severe obesity. For more information, visit

*The effect of bariatric surgery on reducing the risk of colorectal cancer: a meta-analysis 

Michal Janik, Warsaw1, Przemyslaw Sroczynski, Warsaw2, Benjamin Clapp, El Paso TX3, Omar Ghanem, Rochester MN4; Military Institution of Aviation Medicine,1 Military Institute of Aviation Medicine,2 Texas Tech School of Medicine,3 Mayo Clinic College of Medicine4

[i] The Effectiveness and Risks of Bariatric Surgery: An Updated Systematic Review and Meta-analysis, 2003-2012. Accessed from:

[ii] Steele CB, Thomas CC, Henley SJ, et al. Vital Signs: Trends in Incidence of Cancers Associated with Overweight and Obesity — United States, 2005–2014. MMWR Morb Mortal Wkly Rep 2017;66:1052–1058. DOI:

[iii] Centers for Disease Control and Prevention. (2015) The Health Effects of Overweight and Obesity. Accessed from:

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