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One in 20 cancers are attributable to diabetes and being overweight

Most of the cancer cases attributed to these factors occurred in high-income western countries

Ingrid Torjesen

Wednesday, 29 November 2017

Diabetes and high BMI (over 25 kg/m2) were the cause of 5.6% of new cancer cases worldwide in 2012, according to a study* published in The Lancet Diabetes & Endocrinology.

This is equivalent to 792,600 cases of cancer, with 544,300 cases attributable to high BMI (3.9% of all cancers), and 280,100 to diabetes (2% of all cancers).

The study assessed the increase in new cases of 18 cancers based on the prevalence of diabetes and high BMI in 175 countries between 1980 and 2002. The researchers gathered data on the incidence of 12 types of cancer in these countries in 2012 and combined this with data on high BMI and on diabetes. They matched the data sets by age group and sex to take account of age differences using diabetes and BMI data from 2002 to calculate cancer incidence in 2012 attributable to these risks.

Most of the cancer cases attributable to diabetes and high BMI occurred in high-income western countries (38.2%), followed by east and southeast Asian countries (24.1%).

Although cancers are still less common in some low and middle-income countries than in high-income nations, the population of these countries experienced particularly large impacts from diabetes and high BMI. For example, between 9% and 14% of all cancer cases in Mongolia, Egypt, Kuwait, and Vanuatu were due to high BMI and diabetes.

Globally, liver cancer and endometrial cancer contributed the highest number of cancer cases caused by diabetes and high BMI (24.5%, 187,600/766,000 cases, and 38.4% 121,700/317,000 cases, respectively).

Globally, the growing number of people with diabetes between 1980 and 2002 led to 77,000 new cases of attributable cancers in 2012 (26.1% increase). Similar increases in the number of people with high BMI led to 174,040 new cases of weight-related cancers (a 31.9% increase) over the same time. Low- and middle-income countries across Asia and sub-Saharan Africa saw the largest increases in cancers due to diabetes and overweight and obesity, as the levels of diabetes and high BMI in these regions increased substantially between 1980 and 2002.

Both high BMI and diabetes are risk factors for various types of cancer, potentially due to biological changes caused by diabetes and high BMI – such as high insulin, high sugar levels, chronic inflammation, and dysregulated sex hormones such as oestrogen – having adverse effects on the body. With these two risk factors becoming increasingly widespread, the proportion of attributable cancers is set to grow further, the researchers warned.

Using projected prevalence of diabetes and high BMI for 2025 compared with prevalence in 2002, the researchers estimate that the proportion of related cancers will grow by more than 30% in women and 20% in men on average.

Lead author Dr Jonathan Pearson-Stuttard, from Imperial College London, UK, said: “Increases in diabetes and high BMI worldwide could lead to a substantial increase in the proportion of cancers attributable to these risk factors, if nothing is done to reduce them. These projections are particularly alarming when considering the high and increasing cost of cancer and metabolic diseases, and highlight the need to improve control measures, and increase awareness of the link between cancer, diabetes, and high BMI.”

He added: “Clinical and public health efforts should focus on identifying preventive and screening measures for populations and for individual patients. It is important that effective food policies are implemented to tackle the rising prevalence of diabetes, high BMI and the diseases related to these risk factors.”

* Pearson-Stuttard J, Bin Zhou B, Kontis V, et al. Worldwide burden of cancer attributable to diabetes and high body-mass index: a comparative risk assessment. The Lancet Diabetes & Endocrinology, published 28 November 2017. DOI: 10.1016/S2213-8587(17)30366-2

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