A new Lancet study has found that high blood sugar and high BMI (over 25 kg/m2) were the cause of 5.6% new cancer cases in 2012. Calculated on the basis of an individual’s height and weight, BMI is recognised the world over as a measure of obesity.
The study, published in The Lancet Diabetes and Endocrinology found that 544300 cases of cases were attributable to high BMI (equivalent to 3.9% of all cancers), and 280100 were attributable to diabetes (2%). Global estimates suggest that 422 million adults have diabetes and 2.01 billion adults are overweight or obese. High BMI and diabetes are risk factors for various types of cancer, possibly because of the adverse effects on the body of high insulin, high sugar levels, chronic inflammation, and dysregulated sex hormones such as oestrogen, all of which are associated with these diseases. 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.
“As the prevalence of these cancer risk factors increases, 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.” says lead author Dr Jonathan Pearson-Stuttard, Imperial College London. For India the findings are important because with an estimated 62 million diabetics, India is widely known to be the diabetes capital of the world. According to a 2014 article in the Australian medical journal, “ …prevalence of diabetes is predicted to double globally from 171 million in 2000 to 366 million in 2030 with a maximum increase in India. It is predicted that by 2030 diabetes mellitus may afflict up to 79.4 million individuals in India…” Additionally for India the obesity cut-off has been lowered from the global 25 to 22 given the proneness of Indians to truncal obesity that increases the risk of various ailments.
Globally, the growing number of people with diabetes between 1980 and 2002 led to 77000 new cases of attributable cancers in 2012 (26.1% increase). Similar increases in the number of people with high BMI led to 174040 new cases of weight-related cancers (a 31.9% increase) over the same time.
Most of the cancer cases attributable to diabetes and high BMI occurred in high-income western countries (38.2%, 303000/792600 cases), with the second largest proportion occurring in east and southeast Asian countries (24.1%, 190900/792600 cases). Liver cancer and endometrial cancer contributed the highest number of cancer cases caused by diabetes and high BMI (24.5%, 187600/766000 cases, and 38.4% 121700/317000 cases, respectively). However, the number of cases of different cancers varied globally, and in high-income Asia Pacific and east and southeast Asian countries, liver cancer comprised 30.7% and 53.8% of cases respectively, while in high-income western countries, central and eastern Europe, and sub-Saharan Africa breast and endometrial cancers contributed 40.9% of cancer cases.
The proportion of cancers related to diabetes and high BMI is expected to increase even further globally as the prevalence of the two risk factors increases. Using projected prevalence of diabetes and high BMI for 2025 compared with prevalence in 2002, the researchers estimated that the proportion of related cancers will grow by more than 30% in women and 20% in men on average.
