Media Release

Excess weight expected to become 2nd leading preventable cause of cancer after tobacco


A Canadian Cancer Society (CCS)-funded study has found that, unless Canada makes changes, excess weight will become the second leading preventable cause of cancer, following tobacco.

The Canadian Population Attributable Risk of Cancer (ComPARe) study estimated that by 2042, the number of cancer cases due to excess weight will nearly triple, from 7,200 to 21,200. Currently, more than 1 in 2 Canadian adults have excess weight, putting them at increased risk for at least 13 different types of cancer, including breast, colorectal, endometrial and esophageal cancers.

Published today by renowned international journal, Preventive Medicine, and conducted by CCS in collaboration with a pan-Canadian team of experts, the ComPARe study is the first study of its kind in Canada and estimates the current and future burden of more than 30 different cancer types due to more than 20 different modifiable cancer risk factors. The ComPARe study revealed that as many as 4 in 10 cancer cases can be prevented. In addition, the ComPARe study also showed that currently the top five leading preventable causes of cancer are smoking tobacco, followed by physical inactivity, excess weight, low fruit, and sun.

“We are committed to improving and saving lives and preventing cancer is an important part of this commitment,” says Dr Leah Smith, Senior Manager, Surveillance at CCS. “This new study gives us insight into where we can make the biggest difference in cancer prevention for Canadians so they can live their lives to the fullest.”

The ComPARe study also estimates that if we don’t act now, by 2042 almost 60% more cancer cases will be due to preventable causes.

“Results from the ComPARe study will guide further research, inform program development, influence behaviour and assist in advocating for new policies and programs aimed at decreasing the preventable burden of cancer in Canada,” says Dr Christine Friedenreich, principal investigator on the ComPARe study, Scientific Director in the Department of Cancer Epidemiology and Prevention Research at Alberta Health Services and adjunct professor at the University of Calgary.

For example, if more Canadians had a healthy body weight, about 110,600 cases of cancer could be prevented by 2042.

The causes of excess weight are complex and encompass social, economic, physiological, environmental and political factors. No one policy option is going to solve the increasing incidence of overweight and obesity in Canada. CCS believes a comprehensive, societal approach is needed and that Canadians should check with their doctors about what a healthy weight might be for them.

“Together we can help people live long, healthy lives by empowering healthy choices and encouraging government to make healthy living easier for all Canadians,” says Dr Smith. “The results of this study have given us the information we needed to focus our cancer prevention efforts to ensure that we can help stop cancer before it starts.”

For more information on the results of the ComPARe study, please visit or visit to learn more about how you can lower your cancer risk.

About the ComPARe Study

The CCS-funded ComPARe study represents the most comprehensive, up-to-date study on the preventable burden of cancer in Canada. The results will be directly relevant for guiding prevention research, informing program development, influencing behaviour change and advocating for new policies and interventions aimed at decreasing the burden of cancer in Canada. Results will also inform national and provincial policy makers about the risk factors and cancer sites most amenable to intervention(s) and help identify which cancer prevention policies could have the greatest impact.

Backgrounder: Excess weight

Backgrounder: The ComPARe study

About the Canadian Cancer Society

The Canadian Cancer Society is a national community-based organization whose mission is the eradication of cancer and the enhancement of the quality of life of people living with cancer. When you want to know more about cancer, visit our website or call our toll-free, bilingual Cancer Information Service at 1-888-939-3333.

For more information, please contact:

Brooke Kelly
Communications Coordinator
Canadian Cancer Society
National office
Phone: 416-934-5321