Bariatric Surgery Can Reduce Cancer Risk Among Severely Obese Patients

Vinrod Rustgi, MD

New research from Robert Wood Johnson Medical School suggests undergoing bariatric surgery could reduce risk of cancers, particularly obesity-related cancers in obese patients.

A retrospective analysis of claims data from more than 98,000 individuals with severe obesity and nonalcoholic fatty liver disease (NAFLD), results indicate undergoing bariatric surgery reduced risk of all types of cancer by almost 20% and reduced risk of obesity-related cancers by more than 30%.

"We knew that obesity leads to certain problems, including cancer, but no one had ever looked at it the other way around—whether weight loss actually reduced the risk of those cancers," said lead investigator Vinod K. Rustgi, MD, professor of medicine and clinical director of hepatology and Director of the Center for Liver Diseases and Liver Masses, Robert Wood Johnson Medical School, in a statement. "Our study showed that all cancers were decreased, but obesity-related cancers in particular were decreased even more.”

With the obesity pandemic continuing to grow and bariatric surgery representing one of the most efficacious avenues to mitigate obesity-related health risks, Rustgi and a team of colleagues sought to explore the effect of bariatric surgery on cancer risk using data from the Marketscan database. Investigators designed their analysis as a retrospective cohort study of patients 18-64 years of age with newly diagnosed NAFLD and severe obesity from 2007-2017.

In total, investigators identified 2,043,936 patients from within the database with a NAFLD diagnosis from 2008-2017. Of note, 2008 was used to ensure patients had at least 12 months of enrollment within the database prior to NAFLD diagnosis. After application of additional inclusion criteria, 98,090 patients were identified for final analyses.

Among this cohort, 33,435 patients had a BMI of 40 kg/m2 or more and underwent bariatric surgery. The most common type of bariatric surgery was laparoscopic adjustable gastric band (84.23%).

When compared to those who did not undergo surgery, surgery patients were younger (44.01 vs 45.93 years; P <.001), more likely to be women (73.77 vs 62.28%), and less likely to have a history of smoking (6.45 vs 10.13%; P <.001) compared to non-surgery patients.

Among those who did not undergo surgery, investigators identified 1,898 incident cancer cases over 115,890.11 person-years of follow-up. Among those who did undergo bariatric surgery, investigators identified 925 incident cancer cases over 67,389.82 person-years of follow-up. Based on these figures, investigators determined the crude rate of ratio among patients undergoing bariatric surgery was 0.84 (95% CI, 0.77-0.91). Additionally, the inverse probability of treatment weighting (IPTW)-adjusted analyses indicated risk of any cancer and obesity-related cancer was reduced by 18% (HR, 0.82; 95% CI, 0.76-0.89) and 35% (HR, 0.75; 95% CI, 0.56-0.75), respectively among those undergoing bariatric surgery.

Further analysis indicated adjusted risks of any cancer and obesity-related cancer were significantly lower among cirrhotic versus non-cirrhotic patients who underwent bariatric surgery (P <.05). In fully-adjusted cause-specific models, investigates found the risks of hepatocellular carcinoma(HR, 0.48; 95% CI, 0.24-0.89), pancreatic cancer (HR, 0.46; 95% CI, 0.21-0.93), endometrial cancer (HR, 0.49; 95% CI, 0.31-0.73), thyroid cancer (HR, 0.61; 95% CI, 0.41-0.89), and multiple myeloma (HR, 0.33; 95% CI, 0.14-0.69) were all significantly lower among patients who underwent bariatric surgery.

"Understanding the connection between NAFLD and cancer may identify new targets and treatments, such as antidiabetic-, satiety-, or GLP-1-based medications, for chemoprevention in NAFLD/NASH. Though bariatric surgery is a more aggressive approach than lifestyle modifications, surgery may provide additional benefits, such as improved quality of life and decreased long-term healthcare costs," noted investigators in the aforementioned statement.

This study, “Bariatric Surgery Reduces Cancer Risk in Adults with Nonalcoholic Fatty Liver Disease and Severe Obesity,” was published Gastroenterology.