Background: Despite well-established associations between modifiable lifestyle and environmental risk factors and cancer risk, reductions in these risk exposures have not been achieved to produce declines in cancer incidence in Canada. Several factors could explain this lack of change including inadequate awareness among Canadians about the modifiable causes of cancer, and population-based cancer prevention strategies based on outdated information. To guide future cancer prevention programs and policies that will affect cancer incidence significantly, several key components are needed. The first is the quantification of the current preventability of cancer – namely, determining the number of cancer cases that could potentially be prevented through changes in modifiable lifestyle and environmental risk factors. There have been no recent studies conducted across Canada to systematically, comprehensively estimate population attributable risks (PARs) for cancer incidence due to all major modifiable cancer risk factors.

Aim: This project (led by Dr Brenner and Dr. Friedenreich) will quantify the number and proportion of incident cancer cases in Canada, now and in the future, that could be prevented through changes in modifiable lifestyle and environmental exposures associated with cancer. The broad risk factor categories of interest will be: tobacco exposure, dietary factors, energy imbalance, environmental factors, infectious diseases and hormonal therapies. To achieve this goal, the specific objectives will be: Objective 1: To estimate the historical and current prevalence of lifestyle and environmental risk factors for the Canadian adult population that are recognized to be associated with cancer risk. Objective 2: To estimate the current number of incident cancer cases, overall and by type, that are attributable to selected historical risk factors in Canada and by province. Objective 3: To estimate the annual number of incident cancer cases that would occur between 2015 and 2045 at different levels of projected risk factor prevalence. Objective 4: To estimate the potential impact of prevention initiatives on cancer incidence between 2015 and 2045 for different levels of risk factor prevalence.