Researchers Suggest Bariatric Weight Loss Surgery Reduces Risk of Developing Cancer By 32%

The Centers for Disease Control and Prevention (CDC) says that being overweight or having obesity increases the risk of getting cancer .

To reduce this risk, it’s essential to maintain a healthy weight. But it is unknown whether overweight and obese people can reduce the risk of getting cancer through intentional weight loss. Thanks to a recent study, the relationship between weight loss and the risk of getting cancer is now better understood ( 2 ).

The SPLENDID study

The SPLENDID (Surgical Procedures and Long-term Effectiveness in Neoplastic Disease Incidence and Death) research was carried out by the researchers of Cleveland Clinic to evaluate the relationship between intentional weight loss and the risk of getting cancer.

The study was a matched cohort study that involved matching a group of treated individuals with several untreated individuals to make the variable under investigation more comparable between the two groups ( 3 ).

Researchers disclosed that the study was sponsored by a company that makes devices used in weight loss surgeries, Medtronic, and several companies that develop weight loss drugs, such as Eli Lilly and Novartis.

Overview of the SPLENDID research

Patients that underwent bariatric surgery between 2004 and 2017 at a US health facility were matched 1:5 to patients who did not undergo surgery for their obesity. This means every one of the 5053 patients that underwent surgery was matched to 5 people with a similar clinical history.

Since 5053 patients underwent surgery, the total number of participants was 30,318 (25,626 patients didn’t undergo surgery), of which 77% were female and 73% were white. The median age of the participants was 46 years, and the median body mass index (BMI) was 45.

The surgical group was aged 18 years to 80 years and their BMI at the time of surgery was between 35 and 80. They also underwent Roux-en-Y gastric bypass (RYPG) or sleeve gastrectomy (SG), two of the three main types of weight loss surgeries.

Participants in the non-surgical group had similar BMI to those in the surgical group. While they had no surgery, they were encouraged to lose weight through other means.

Follow-up was done for 10 years and ended in February 2021. The participants were screened for the 13 types of cancers (breast, colon, kidney, liver, and so on) associated with obesity.

Results of the research

At the end of the study, the mean difference in body weight between the surgical group and non-surgical group was 54.7 pounds (24.8 kg). This represents a 19.2% greater weight loss in the surgical group. 

Also, only 2.9% of the surgery group had any one of the obesity-linked cancer compared to 4.9% of the non-surgical group that had cancer. 0.8% of the surgery group died from an obesity-related cancer, while it was 1.4% for the non-surgical group.

So, the bariatric surgery group had a 32% lower risk of developing cancer and a 48% lower risk of dying from cancer compared to the non-surgical group.

Conclusions that can be drawn from the study

Understanding Bariatric Surgery

The results of the study clearly showed that losing weight can significantly reduce the occurrence of obesity-related cancers. The more weight lost, the more the cancer risk is reduced. Also, it would seem significant weight loss is needed to reduce cancer risk appreciably.

Bariatric surgery is known to sustain more than a 20% reduction in body weight a decade after the procedure ( 4 ). This is far more than what overweight and obese people can lose through exercise and diet alone.

However, bariatric surgery isn’t an option for most obese people as the procedure is done only on obese people with serious weight-related health problems ( 5 ). As such, other weight-loss methods will have to be utilized.

While this study is focused on bariatric surgery, the effect of “clinically significant” weight loss should the same regardless of the weight loss method utilized. Therefore, overweight and obese people should strive to lose weight however they can, be it through diet, exercise, or medications.

Limitations of the research

Since the research is a cohort study, it can only identify associations and correlations. Cause and effect can’t be demonstrated. The participants’ lifestyle was also not monitored, and it is unknown what impact it had on the cancer risk of the participants.

Researchers also didn’t track physical activity, dietary habits, exposure to UV light, environmental carcinogens, and cancer-causing pathogens. Also, most of the participants were white, and the results of this study may not be generalizable to people of other races or ethnicity.

Understanding Bariatric Surgery

Bariatric surgery is a weight-loss surgery performed as a last resort to help people lose weight when other weight-loss methods have failed ( 6 ).

To qualify for it, patients must have a BMI of 40 or higher (classified as extreme obesity) or have a BMI of 30 to 39.9 (obesity) and suffer from a severe weight-related health problem such as high blood pressure, type 2 diabetes, or severe sleep apnea ( 5 ).

People who have undergone the procedure must make permanent changes to their diet and lifestyle to enjoy the long-term success of the surgery.


1. Centers for Disease Control and Prevention. Obesity and Cancer.

2. Aminian A, Wilson R, Al-Kurd A, Tu C, Milinovich A, Kroh M, Rosenthal RJ, Brethauer SA, Schauer PR, Kattan MW, Brown JC, Berger NA, Abraham J, Nissen SE. Association of Bariatric Surgery With Cancer Risk and Mortality in Adults With Obesity. JAMA. 2022 Jun 28;327(24):2423-2433. doi: 10.1001/jama.2022.9009. PMID: 35657620; PMCID: PMC9166218.

3. Brazauskas R, Logan BR. Observational Studies: Matching or Regression? Biol Blood Marrow Transplant. 2016 Mar;22(3):557-63. doi: 10.1016/j.bbmt.2015.12.005. Epub 2015 Dec 19. PMID: 26712591; PMCID: PMC4756459.

4. Maciejewski ML, Arterburn DE, Van Scoyoc L, Smith VA, Yancy WS Jr, Weidenbacher HJ, Livingston EH, Olsen MK. Bariatric Surgery and Long-term Durability of Weight Loss. JAMA Surg. 2016 Nov 1;151(11):1046-1055. doi: 10.1001/jamasurg.2016.2317. PMID: 27579793; PMCID: PMC5112115.

5. American Society for Metabolic and Bariatric Surgery. Who is a Candidate for Bariatric Surgery?

6. Mayo Clinic. Bariatric Surgery.