Effective glucose control is important in reducing the risk of cancer in obesity and type 2 diabetes. Substantial, lasting weight loss appears to provide protection against cancer, but with effective glucose control, the number of cancer cases also drops dramatically, a University of Gothenburg study shows.
It’s a known fact that obesity is a risk factor for both type 2 diabetes and several types of cancers. Similarly, intentional weight loss through, for example, bariatric surgery often leads to diabetes improvement, and many patients end up having normal blood glucose control. For obese patients, the risk of cancer can also be reduced after significant and long-lasting weight loss. However, there have been relatively few studies on the association between weight loss, cancer risk, and glucose control in patients with obesity and type 2 diabetes. This study, published in the journal Diabetes Care, used data from the “SOS” (Swedish Obese Subjects) intervention trial, which is led and coordinated by the University of Gothenburg, as well as data from other sources, such as the Swedish Cancer Registry.
60% lower risk of cancer
The researchers studied a group of 393 people with type 2 diabetes who underwent bariatric surgery, and compared them to a control group of 308 people with the same clinical characteristics; in other words, they were extremely obese and had type 2 diabetes, but hadn’t undergone bariatric surgery. Regarding other aspects such as gender composition, blood glucose, and smoking habits, both groups were similar. In the surgery group, 68 people (approximately 17%) developed cancer in parallel with significant weight loss. The corresponding emergent cancer cases in the control group added up to 74 (24%), while these individuals maintained their extreme obesity condition. The median follow-up period was 21 years. Overall, the risk of cancer was 37% lower in the group that underwent bariatric surgery.
However, the greatest difference was observed when cancer risk was analyzed in patients who achieved normal glucose control and didn’t show diabetes relapse over a 10-year period. Among these patients, the incidence of cancer was only in 12 of 102 (12%), against 75 of 335 (22%) in the group whose diabetes had reappeared during the same period. Therefore, the results show a 60% reduction in cancer risk in the group in which normal glucose control was maintained for 10 years.
Guidance to prevent cancer
“What we see is that among patients with type 2 diabetes, many cases of cancer are preventable. These results are an important contribution that improves our understanding of the connection between glucose control and cancer prevention,” Kajsa Sjöholm affirmed, associate professor of Molecular Medicine at University of Gothenburg Sahlgrenska Academy, and first author of the study.
Magdalena Taube, associate professor of Molecular Medicine at University of Gothenburg Sahlgrenska Academy, is the lead author of the study, and she noted: “The global epidemic of obesity and diabetes leads to an increased risk of cancer, as well as an increased risk of early death. Over the next 10 to 15 years, obesity is estimated to cause more cancer cases than smoking in several countries. This is a clear example of the severity of the condition. Strategies are needed to prevent this development, and our results may provide a vital guide to cancer prevention in patients with obesity and type 2 diabetes.”
Date: December 4th, 2021
Reference: 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. 2021 Nov 19:dc211335.
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