Bariatric surgery may reduce cancer risk in patients with obesity and type 2 diabetes

Research findings derived from a Swedish Obese Subjects (SOS) study, published in Diabetes Care, found that 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. 

The study examined long-term outcomes after bariatric surgery versus usual care in people with obesity. Researchers examined outcomes of 701 patients with obesity and T2D 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 analysed 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).

Compared with the control group, bariatric surgery was associated with a significantly reduced incidence of cancer in women, (HR, 0.58; 95% CI, 0.38–0.90; P =.016). However, with bariatric surgery in men, there was no similar association (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).

The ascertainment of diabetes diagnoses was a limitation of the study, which were based on a single time point 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.”