Weight-Loss Surgery Slashes Cancer Risk and Mortality in People With Obesity

Doctor With Obese Patient

According to new research, obese people were twice as likely to develop certain types of cancer and 3.5x more likely to die from it, than those who had weight-loss surgery.

According to the Centers for Disease Control and Prevention, 41.9% of U.S. adults are obese, with 9.2% severely obese. Obesity contributes to a wide array of health problems, including cancer. In fact, according to the CDC, being overweight or having obesity is linked to a higher risk of getting 13 different types of cancer.

People that are severely obese and have trouble losing weight sometimes turn to weight-loss surgery. Two common types these days are gastric bypass surgery and sleeve gastrectomy. In gastric bypass surgery, the top of the stomach is turned into a small pouch and connected to your small intestine further down. This bypasses your stomach, reducing the calories absorbed. In sleeve gastrectomy, approximately 80% of the stomach is removed, leaving a tube-shaped stomach that is similar in size and shape to a banana.

Individuals with obesity were at least two times more likely to develop certain types of cancer and 3.5 times more likely to die from the disease than those who had weight-loss surgery, according to a new study presented today (June 7, 2022) at the American Society for Metabolic and Bariatric Surgery (ASMBS) Annual Meeting (#ASMBS2022).

Researchers found that after having weight-loss surgery, patients saw big reductions in the incidence of breast cancer (1.4% vs 2.7%), gynecologic cancer (0.4% vs 2.6%), kidney cancer (0.10% vs. 0.80%), brain cancer (0.20% vs 0.90%), lung cancer (0.20% vs 0.60%) and thyroid cancer (0.10% vs 0.70%).

The 10-year incidence of any new cancer in the bariatric group was much lower (5.2% vs. 12.2%) and the 10-year survival rate was much higher (92.9% vs. 78.9%) than the non-surgical group. The retrospective study included 1,620 patients who had either gastric bypass surgery (1,265 patients) or sleeve gastrectomy (355 patients) between September 2001 and December 2019, and 2,156 patients matched based on age, sex, and body mass index (BMI), who did not have surgery. Researchers estimate surgery patients lost about 60% of their excess weight at 10 years.

“We knew bariatric surgery would reduce cancer risk based on previous studies, but what surprised us was the extent of that reduction in certain cancers,” said study-co-author Jared R. Miller, MD, a general and bariatric surgeon at Gundersen Lutheran Health System. “The benefits of cancer risk reduction through weight-loss surgery cannot be ignored and should be a consideration for patients with obesity and at high risk for cancer.”

The U.S. Centers for Disease Control and Prevention (CDC) estimates more than 650,000 obesity-associated cancers occur in the United States each year. From 2005 to 2014, most cancers associated with overweight and obesity increased by 7%, while the rate of new cancers not associated with excess weight dropped by 13%. According to the American Society of Clinical Oncology (ASCO), obesity is a major unrecognized risk factor for cancer and is associated with worsened prognosis after cancer diagnosis.

Overweight and obesity can cause changes in the body that could lead to cancer, including long-lasting inflammation and high insulin levels. The risk of cancer increases the more excess weight a person gains and the longer they have overweight or obesity.

“The data continues to mount – when you treat obesity, you prevent certain cancers,” said Shanu Kothari, MD, President, ASMBS, who was not involved in the study. “Weight-loss surgery has proven to be the most effective long-term treatment for obesity and now it’s increasingly being looked upon as a preventative treatment, not only for cancer, but heart disease, stroke and type 2 diabetes too.”

In 2016, the ASMBS issued a position statement on the relationship between obesity and cancer, and the role of bariatric surgery and the impact of weight loss not only on cancer risk, but on survivorship after treatment.

Reference: “Cancer Incidence, Type, and Survival after Bariatric Surgery” by Jared R. Miller, MD, Alec J. Fitzsimmons, MPH, Andrew J. Borgert, PhD, Katelyn M. Mellion, MD, Joshua D. Pfeiffer, MD and Brandon T. Grover, DO, FACS, 7 June 2022, American Society for Metabolic and Bariatric Surgery Annual Meeting.

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.[1],[2],[3] 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.


  1. The Effectiveness and Risks of Bariatric Surgery: An Updated Systematic Review and Meta-analysis, 2003-2012. DOI: 10.1001/jamasurg.2013.3654
  2. 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: 10.15585/mmwr.mm6639e1
  3. Centers for Disease Control and Prevention. (2015) The Health Effects of Overweight and Obesity. Accessed from: https://www.cdc.gov/healthyweight/effects/index.html


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.

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