What Prevention Means

Identifying how many cases of cancer could be prevented by lifestyle steps is important to policymakers and the average individual. It’s important to remember that the term prevention is population based.

Methods for preventability estimates

When we at AICR use the term “prevention” it is in terms of the US population.  AICR/WCRF preventability estimates are calculated using information on:

  • Cancer risk associated with an exposure, such as alcohol 
  • Prevalence of that exposure, such as the number of people in the US who consume alcohol
  • US incidence of different cancers, such as the annual number of cases of the cancer types that link to alcohol

The methods used to calculate the estimates can be found in Appendix A of the Policy Report. In brief, the estimates were made for lifestyle factors judged to be convincing or probable modifiers of cancer risk in AICR/WCRF research reports, with a few exceptions. There are 13 cancers included.

These two pieces of information were used to estimate preventability for each lifestyle factor:

  • Highest versus lowest risk estimates were used for cancer risk.
  • Information on prevalence of lifestyle factors was obtained from national surveys.

Prevention and reducing risk

All of us are at some level of risk for developing cancer at some point in our lives. Risk increases with age and each cancer has its own unique risk factors.

It’s difficult to know how much risk each person faces. There are smokers who never get lung cancer and healthy, non-smoking individuals who get diagnosed with this cancer. There are also people with obesity who never develop colorectal cancer and lean individuals who do.

Preventability estimates can be powerful gauges of lifestyle steps that can increase or decrease cancer risk. To prevent breast cancer, for example, if the entire US population were to avoid alcohol, keep to a healthy weight and exercise daily, AICR estimates there would be 33 percent fewer US cases of breast cancer cases. For individuals, it means there are ways to reduce your risk.