Link Between Cancer and Diabetes, High Body Mass Index
According to the International Agency for Research on Cancer and the World Cancer Research Fund, there is a causal association between a high body mass index (BMI) and 14 cancers, including colorectal, gallbladder, pancreatic, kidney, liver, endometrial, postmenopausal breast, ovarian, gastric cardia, thyroid, esophageal, and multiple myeloma. A new study evaluating the proportion of cancers attributable to the combined effects of diabetes and a high BMI, defined as over 25 kg/m2, has found that 5.6% of new cancer cases worldwide in 2012—about 792,600 cases—were attributable to diabetes and a high BMI as independent risk factors.
Individually, a high BMI was responsible for twice as many cancer cases as diabetes—544,300 vs 280,100 cases, respectively. Unless obesity and diabetes rates are reduced, the study authors project substantial increases in the worldwide cancer burden by 2025, especially in gallbladder, liver, and endometrial cancers. The study by Pearson-Stuttard et al was published in The Lancet Diabetes & Endocrinology.
Study Methodology
The researchers reviewed the published literature that summarized associations of diabetes and a high BMI with site-specific cancers. Using the prevalence of diabetes and categories of BMI and relative risks for their associations with the cancer identified from published meta-analyses, the researchers gathered data on the incidence of 12 cancers from 175 countries in 2012. They then used GLOBOCAN cancer incidence data to estimate the number of cancer cases attributable to the two risk factors. They also estimated the number of cancer cases in 2012 that were attributable to increases in the prevalence of diabetes and a high BMI from 1980 to 2002. All analyses were done at the individual country level and grouped by region for reporting.
Study Findings
The researchers estimated that 5.6% of all incident cancers in 2012 were attributable to the combined effects of diabetes and a high BMI as independent risk factors, corresponding to 792,600 new cases of cancer. Of the 766,000 cases of liver cancer, 187,600 (24.5%) of those cases and 121,700 (38.4%) of 317,000 cases of endometrial cancer were attributable to these risk factors. About 4.5% (626,900 new cases) of all incident cancers assessed were attributable to diabetes and a high BMI combined.
Individually, a high BMI (544,300 cases) was responsible for twice as many cancer cases as diabetes (280,100 cases); 26.1% of diabetes-related cancers (equating to 77,000 new cases) and 31.9% of high BMI-related cancers (174,040 new cases) were attributable to increases in the prevalence of these risk factors from 1980 to 2002.
Cancer cases attributable to diabetes and a high BMI combined were almost twice as common in women (496,700 cases) as in men (295,900 cases).
“As the prevalence of these cancer risk factors increases, clinical and public health efforts should focus on identifying optimal preventive and screening measures for whole populations and individual patients,” concluded the study authors.
Raising Public Awareness About the Obesity/Cancer Link
This past October, ASCO published the results of its National Cancer Opinion Survey, which polled over 4,000 adults nationwide regarding their views on cancer research and care. The survey found that only 31% of respondents identified obesity as a risk factor for cancer, even though obesity is expected to soon overtake smoking as the greatest preventable cause of the disease.
In addition, the majority of Americans are not taking some important preventive actions to reduce their risk of cancer. For example, fewer than half of those polled said they are doing the following to reduce their risk of cancer:
- Maintaining a healthy weight: 41%
- Exercising regularly: 48%.
“The results from The Lancet Diabetes & Endocrinology study add another reason for the general public to be concerned about the health risks associated with obesity, which clearly include cancer,” said ASCO’s Chief Executive Officer Clifford Hudis, MD, FACP, FASCO. “ASCO’s recent National Cancer Opinion Survey found that fewer than one in three Americans realize obesity is a risk factor for cancer, even though it is the second leading preventable cause of the disease. Armed with this increasing recognition of its medical risks, we must work together across medical disciplines to help Americans address this challenge.”
Jonathan Pearson-Stuttard, BMBCh, of the School of Public Health at the Imperial College London in England, is the corresponding author of this study.
Majid Ezzati, PhD, coauthor of this study, declared a charitable grant from the Young Health Programme of AstraZeneca as well as personal fees from Third Bridge, Scor, and Prudential, outside the submitted work.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
