Non-communicable diseases - AQARisk factors and causal mechanisms

Correlation

Scientists look for patterns in data.

Research has established links between cancer and various lifestyle factors, chemicals produced in the body, or that enter the human body, and chemicals in the environment.

Scientists have established several causal mechanisms for risk factors.

Below is an example of how risk factors have been found. This has come from studies on smoking cigarettes and lung cancer.

Historically, in the UK, a pattern can be seen between the number of people who smoke cigarettes and the number of smoking related deaths.

As the number of cigarettes smoked has decreased over the years, the incidence of smoking related deaths has decreased also.

There is a clear association, called a correlation, between the variables. As one decreases, so does the other.

Correlation and cause

If there is a correlation between a particular factor and an outcome, it does not mean that the factor necessarily causes the outcome. Scientists must look for a possible mechanism by which the factor could be the likely cause.

In the case of lung cancer, analyses of cigarette smoke have shown that at least 70 of the chemicals present in smoke will cause cancer in laboratory animals which establishes a causal link.

Learn more about risk factors for non-communicable diseases with Dr Alex Lathbridge.

Listen to the full series on BBC Sounds.