“It is difficult to make predictions, especially about the future.” – Danish proverb
In fact, we (the researchers from the ComPARe study) did not predict what the future cancer burden would be. Instead, we projected what the future cancer burden could be, given the past trend of cancer incidence and the prevalence of risk factors. We also projected how we could reduce the number of cancer cases in the future through healthy living and policies to protect the public.
Three pieces of information are crucial to make such projections: the cancer incidence, the risk factor prevalence, and the intervention scenarios.
- First, we projected future cancer incidence (how many cancer cases there will be) in Canada based on past information on the age and birth year of Canadians who have been diagnosed with cancer and the year of their diagnosis.
- Second, we projected the future risk factor prevalence (how common the risk factors are) based on historical observations. For example, we observed a decreasing trend in smoking from 1994 to 2011. We assumed that the decreasing trend will continue in the future.
- Third, we developed a series of intervention scenarios. We can imagine them as several parallel universes, and within each universe an intervention would be implemented in the future to lessen the effect of a risk factor. By comparing these parallel universes to the ones without that intervention, we could estimate the number of cancers that could be prevented.
We estimated that about 100,000 of the cancer cases diagnosed in 2042 could be due to modifiable risk factors. Comparing to 2015, smoking would remain the most significant risk factor, with 47,000 cancers in 2042 due to smoking (32,700 cancers in 2015). If the current epidemic of excess body weight continues to rise, obesity could rise to the second most significant risk factor, from contributing to 5,700 cancers in 2015 to 17,400 cancers in 2042.
Almost 40,000 cancers could be prevented under the various intervention scenarios we developed. These interventions include:
- reducing the prevalence of the following risk factors by 50%: smoking tobacco, alcohol drinking, inadequate physical activity, sedentary behaviours, low vegetable and fruit consumption, suntanning, sunbathing, indoor tanning, infection of HBV, HCV, and Helicobacter pylori
- reducing the prevalence of obesity by 25%
- lowering daily intake of processed meat and red meat by 1 and 2 servings
- mitigating all household radon exposures above 100 Bq/m3 to 50 Bq/m3
- reducing air pollution (PM2.5) by 50%
- increasing HPV vaccination coverage to 80% among school-aged girls and boys
These intervention scenarios reveal the possibility of a bright future with fewer cancers, but it will only become reality if we act quickly to help Canadians live healthier lives in safer environments. Let’s start making the change, today.
Yibing Ruan, PhD, MPH, CPH
Department of Cancer Epidemiology and Prevention Research
Alberta Health Services
ComPARe Study Lifestyle Node