Study Links Obesity to Certain Cancers

Associations between adiposity and 11 types of cancers were supported by strong evidence, according to a new meta-analysis.

Researchers evaluated the strength and validity of evidence for the association between adiposity and risk of developing or dying from cancer in a meta-analysis of 49 papers, which included 204 meta-analyses summarizing 2179 individual study estimates from 507 unique cohort or case-control studies. The evidence of each study was graded as strong, highly suggestive, suggestive, or weak.
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The analysis showed that increases in body mass index were associated with a higher risk of developing esophageal adenocarcinoma, kidney cancer, multiple myeloma, colon and rectal cancer in men, developing biliary tract system and pancreatic cancer, and endometrial cancer in premenopausal women.

“The increase in the risk of developing cancer for every 5 kg/m2 increase in body mass index ranged from 9% (relative risk 1.09, 95% confidence interval 1.06 to 1.13) for rectal cancer among men to 56% (1.56, 1.34 to 1.81) for biliary tract system cancer,” the researchers wrote.

In addition, researchers found that every 5 kg of weight gained in postmenopausal women who never used hormone replacement therapy was associated with an 11% increased risk for developing breast cancer. Endometrial cancer risk in postmenopausal women who never used hormone replacement therapy increased by 21% for every 0.1 increase in waist-to-hip ratio.

Strong evidence was also found linking colorectal cancer to weight gain and body mass index to gallbladder, gastric cardia, ovarian cancer, and multiple myeloma mortality.

Overall, esophageal adenocarcinoma, multiple myeloma, and cancers of the gastric cardia, colon, rectum, biliary tract system, pancreas, breast, endometrium, ovary, and kidney were associated with obesity. Associations between adiposity and other types of cancer remained uncertain due to a lack of strong evidence, according to the researchers.

“To draw firmer conclusions, we need prospective studies and large consortiums with better assessment of the changing nature of body fatness and with comprehensive standardized reporting of analyses,” the researchers concluded. “As obesity becomes one of the greatest public health problems worldwide, evidence of the strength of the associations between obesity and cancer may allow finer selection of people at high risk, who could be selected for personalized primary and secondary prevention strategies.

—Melissa Weiss


Kyrgiou M, Kalliala I, Markozannes G, et al. Adiposity and caner at major anatomical sites: umbrella review of the literature [published online February 28, 2017]. BMJ. doi: