Issue: March 2018
Perspective from Steven Heymsfield, MD
January 29, 2018
2 min read

Rise in Canadian obesity rate may increase country’s cancer burden

Issue: March 2018
Perspective from Steven Heymsfield, MD
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Excess body weight contributes to nearly 12% of cancer cases in Canada, and weight-loss interventions could potentially prevent more than 58,000 cancer cases over 30 years, according to findings presented at the American Association for Cancer Research Special Conference, Obesity and Cancer: Mechanisms Underlying Etiology and Outcomes.

“Several cancer sites have strong associations with excess body weight, yet the number of Canadians who are overweight or obese is increasing,” Darren Brenner, PhD, assistant professor at University of Calgary Cumming School of Medicine in Alberta, Canada, told Endocrine Today. “By returning to body weight levels of 1990 over the next 30 years, we could avoid nearly 60,000 Canadians having a diagnosis of cancer.”

As part of the Canadian Population Attributable Risk of Cancer Project, Brenner and colleagues estimated how many new cases of cancer are caused by 25 different risk factors, including lifestyle factors and excess body weight, defined as BMI at least 25 kg/m². Researchers assessed prevalence data for overweight and obesity and cancer incidence using Canadian population-based surveys and age- and sex-specific incidence data from the Canadian Cancer Registry. Researchers combined projected overweight and obesity prevalence trends with projected cancer incidence trends to 2042, based on historical data, to determine the future cancer burden attributable to excess body weight. To estimate the potential for cancer prevention with a reduction in overweight and obesity prevalence, researchers modeled the potential impact fraction of the associated cancers based on counterfactual interventions to reduce the prevalence of both overweight and obesity by 10%, 25% and 50%.

Researchers estimated that 3,886 cancer cases in men and 4,740 cancer cases in women were attributable to excess body weight. The population attributable risk for excess body weight was 9.4% among the 14 associated cancer sites in Canada in 2012. In sensitivity analyses, researchers found that estimates of cancer cases attributable to excess weight could reach 4,648 cases in men and 5,868 cases in women due to self-report bias.

In modeling trends, researchers found that if overweight and obesity prevalence were reduced by 10% by 2042, 1,660 cancer cases could be prevented. If overweight and obesity prevalence were reduced by 25% or 50% by the same time, 4,150 and 8,300 cancer cases would be prevented, according to researchers. Cumulatively, 10%, 25% and 50% reductions in overweight and obesity would prevent 11,966, 29,914 and 59,829 cancer cases by 2042, respectively.

In a press release announcing the findings, Brenner called the data “alarming estimates of the consequences of inaction in Canada.”


“The results add additional weight to the importance of weight management as part of standard clinical care,” Brenner said. – by Regina Schaffer

For more information:

Darren Brenner, PhD, can be reached at Department of Cancer Epidemiology and Prevention Research, CancerControl Alberta - Alberta Health Services,
. SW, Calgary, Alberta, T2S 3C3; email:


Brenner D, et al. Abstract PR01. Presented at: American Association for Cancer Research Special Conference; Jan. 27-30, 2018; Austin, Texas.

Disclosures: This study was funded by a Canadian Cancer Society Research Institute Partner Prevention Research grant. Brenner reports no relevant financial disclosures.