Population health research

In population health research, scientists study groups of people to understand why some people are healthier than others and how common characteristics affect cancer risk and long-term health. These characteristics could be age, gender or health condition, or include factors such as geographic location and lifestyle choices. To learn more about health and disease among a specific population, these studies often include large numbers of people over long periods of time. By studying populations in this way, researchers learn how to improve cancer prevention, screening and care.

In recent decades we've learned a lot about cancer prevention, but there is much more to learn about how the disease develops and how to stop it before it starts. Cancer prevention studies help researchers understand what factors prevent or lower our risk of developing cancer. These studies often follow large groups of people over years, or even decades, to allow researchers to study how our environment and lifestyles impact long-term health. Below are some of the risks that researchers might study.

This could include exposure to cancer-causing chemicals (known as carcinogens) such as asbestos or outdoor air pollution.

Studies have shown that what we eat and drink affects our risk of developing cancer. For example, a diet that includes red or processed meat increases the risk of certain cancers, as does drinking any type of alcohol.

Physical activity is known to lower the risk of several types of cancer, and benefits cancer survivors. Meanwhile, sedentary behaviour – being inactive for long periods of time – has been linked with an increased risk for certain cancers.

In recent decades, our understanding of what influences health and the cancer experience has grown dramatically. Now, we understand that health is influenced by many biological, social and economic factors.

The health of any group of people is influenced by many factors, from our biology and lifestyle choices, to where we live, and the social structures that influence what opportunities and services are available to us.

These factors are called social determinants of health. They include, but are not limited to:

• income and social status
• employment and working conditions
• education and literacy
• childhood experiences
• physical environments
• social supports and coping skills
• healthy behaviours
• access to health services
• biology and genetics
• gender
• culture and race

At first glance, it might not be obvious how these social and economic factors impact health. But on their own and in combination, these factors influence how people experience health and the healthcare system.

For example, Canadians who live in remote areas may not have the same access to cancer screening as those who live in cities. Meanwhile, those who have experienced discrimination or racism in the health system might be less likely to seek care when they need it.

By studying how social determinants of health influence the cancer experience, researchers hope to help everyone get the care they need, no matter who they are or where they live.

It is impossible to study every individual within any population. Instead, researchers select a sample and use these results to predict what is likely to happen in the larger population.

If the sample size is large, the group is more likely be a good representation of the overall population, and the results are more likely to be an accurate reflection of what would happen in the real world.

For this to be the case, research studies need to include participants that reflect the overall population. But historically there have been notable gaps, with women and racial and ethnic minorities often missing from medical research. While efforts have been made to improve diversity in health research, clinical trial participants are still overwhelmingly white. Teenagers and young adults, who experience cancer very differently from children or older adults, are another group often missing from clinical trials. This group can struggle to secure a diagnosis or access care because they don't fit neatly into pediatric or adult groups.