Bariatric Surgery Associated with Lower Cancer Risk in Obesity and Diabetes

Kajsa Sjöholm, PhD, and Magdalena Taube, PhD

New research from a Swedish cohort study suggests patients with obesity and diabetes who undergo bariatric surgery could dramatically reduce their risk of cancer.

An analysis of data from the matched, prospective Swedish Obese Subjects (SOS) study, which included a median of 21 years of follow-up data, results indicated those who underwent bariatric surgery lowered their risk of cancer by 37%, but also suggest those achieving normal glucose control and diabetes remission reduced their risk of cancer by 60%.

“The global epidemic of both obesity and diabetes leads to an increased risk of cancer, as well as an increased risk of premature death. It has been estimated that, over the next 10 to 15 years, obesity may cause more cancer cases than smoking in several countries. This is a clear illustration of how serious the condition is,” said Magdalena Taube, PhD, associate professor of Molecular Medicine at Sahlgrenska Academy, University of Gothenburg, in a statement. “Strategies are need to prevent this development, and our results can provide vital guidance for prevention of cancer in patients with obesity and type 2 diabetes.”

With an interest in shrinking an apparent knowledge gap related to the effects of bariatric surgery on cancer risk among patients with both obesity and diabetes, the current study was designed Taube and colleagues from the University of Gothenburg to assess incidence of cancer among patients from the SOS study. A nonrandomized, parallel assignment study launched in 1987, the SOS study enrolled more than 4000 patients, who were followed from enrollment through 2005. Results of the study suggested bariatric surgery was associated with meaningful reductions in body weight and mortality among patients with severe obesity.

For the current study, investigators included 701 patients with obesity and diabetes from the original SOS study. This cohort included 393 patients who underwent bariatric surgery and 308 who received conventional treatment. The median follow-up of this cohort was 21.3 (IQR, 17.6-24.8) years with a maximum follow-up of 30.7 years. Overall, 17% (n=68) of the bariatric surgery group developed cancer and 24% (n=74) of the conventional treatment group developed cancer.

Upon analysis, results indicated the incidence rate of first-time cancer was 9.1 (95% CI, 7.2-11.5) per 1000 person-years among patients with obesity and diabetes who underwent bariatric surgery compared to 14.1 (95% CI, 11.2-17.7) per 1000 person-years in those who received conventional treatment (aHR, 0.63 [95% CI, 0.44-0.89]; P=.008). Investigators pointed out surgery was associated with a reduction in cancer incidence among women (aHR, 0.58 [95% CI, 0.38-0.90]; P, but sex-treatment interaction was nonsignificant (P=.630). Further analysis suggested those who achieved diabetes remission at the 10-year follow-up suggested these patients experienced an even greater reduction in cancer incidence (aHR, 0.40 [95% CI, 0.22-0.75]; P=.003).

“What we see is that, among patients with type 2 diabetes, many cancer cases are preventable. These results are an important contribution that enhances our understanding of the connection between glucose control and cancer prevention,” added Kajsa Sjöholm, PhD, associate professor of Molecular Medicine at Sahlgrenska Academy, University of Gothenburg, in the aforementioned statement.

This study, “Association of Bariatric Surgery With Cancer Incidence in Patients With Obesity and Diabetes: Long-Term Results From the Swedish Obese Subjects Study,” was published in Diabetes Care.