In people with obesity and type 2 diabetes (T2D), bariatric surgery may play a role in cancer prevention. “Durable” remission of T2D is often achieved after weight-loss surgery, further associating it with a reduced cancer risk. These study findings were published in Diabetes Care.
The research findings were derived from the Swedish Obese Subjects (SOS) study, which examined long-term outcomes after bariatric surgery versus usual care in people with obesity. Researchers examined outcomes of 701 patients with obesity and type 2 diabetes at baseline. A total of 393 of these patients (mean age, 48.6 years) underwent bariatric surgery while 308 patients (mean age, 50.5 years) received conventional obesity treatment.. The investigators analyzed cancer events, reported in the Swedish National Cancer Register, over the median follow-up of 21.3 years.
In patients treated with bariatric surgery, the incidence rate for first-time cancer during the follow-up period was 9.1 per 1,000 person-years (95% CI, 7.2–11.5). In contrast, the incidence rate for first-time cancer in patients treated with usual obesity care was 14.1 per 1,000 person-years (95% CI, 11.2–17.7). The incidence rate for first-time cancer diagnosis was significantly lower in the patients treated with bariatric surgery (adjusted hazard ratio [HR], 0.63; 95% CI, 0.44–0.89; P =.008).
Bariatric surgery was associated with a significantly reduced incidence of cancer in women, compared with the control group (HR, 0.58; 95% CI, 0.38–0.90; P =.016). There was no similar association with bariatric surgery in men (HR, 0.79; 95% CI, 0.46-1.38; P =.0413). Diabetes remission at 10 years follow-up was also associated with a reduction in cancer incidence (HR, 0.40; 95% CI, 0.22–0.74; P =.003).
A limitation of the study was the ascertainment of diabetes diagnoses, which were based on a single timepoint measurement and/or the use of a diabetes medication. Additionally, the majority of participants in the surgery group had received vertical banded gastroplasty or banding, which is rarely used today. High postoperative mortality following bariatric surgery was reported during the original SOS study.
“In conclusion, with increasing rates of obesity and diabetes worldwide, a greater emphasis on cancer prevention strategies is needed,” the researchers wrote. “Bariatric surgery may greatly reduce the risk of cancer among patients with obesity and diabetes. Durable diabetes remission seems imperative for cancer prevention in patients with obesity and diabetes.”
Disclosure: This clinical trial was supported in part by Novo Nordisk. One author declared affiliations with a pharmaceutical company. Please see the original reference for a full list of authors’ disclosures.
Sjöholm K, Carlsson LMS, Svensson PA, et al. Association of bariatric surgery with cancer incidence in patients with obesity and diabetes: long-term results from the Swedish Obese Subjects study. Diabetes Care. Published online November 19, 2021. doi:10.2337/dc21-1335