Cancer projections and common risk factors to avoid

Dr Niamh Bambury

Aspire Fellow in Cancer Intelligence, National Cancer Registry Ireland and National Cancer Control Programme

Due to population growth and ageing, it is expected that the number of cancer cases will increase significantly, with the most optimistic projections being 50% higher by 2045.

The National Cancer Registry Ireland (NCRI) collects information on all cancers in Ireland since 1994. This information is analysed to produce statistics about cancer every year. In the most recent NCRI report, there was an average of 24,327 cases of cancer diagnosed each year between 2018–20, excluding non-melanoma skin cancers.

Modifiable cancer risk factors

Cancer is the most common cause of death in Ireland with approximately 30% of all deaths attributable to cancer. There are many factors contributing to the development of cancer. Some of these factors are unavoidable, such as one’s age, sex, race, ethnicity, family history and genetics.

However, there are other risk factors associated with lifestyle that are termed ‘modifiable risk factors,’ meaning, if you avoid them, you lower your risk of cancer — irrespective of the factors you can’t avoid.

A 2020 report by the NCRI examined the potential link between a number of modifiable risk factors and cancer. The report found that 3 out of 10 cancers were attributable to one or more of the modifiable risk factors examined. This suggests that at least 6,240 cancer cases were potentially preventable in Ireland in 2016. The two biggest risk factors associated with cancer were smoking and overweight/obesity.

Smoking is the most common risk factor

Smoking — including passive smoking — was associated with 13% of cancers (2,779 cases). Smoking is attributable to 76% of lung cancer cases. As the population increases, the NCRI projects that by 2035, the number of cancers due to smoking will rise to 4,662 cases.

Smoking is attributable to 76% of lung cancer cases.

Obesity as a common risk factor

Overweight/obesity is associated with 5% of cancers (1,061 cases). It is attributable to 23% of kidney cancer cases. By 2035, the number of cancers due to overweight/obesity is projected to rise to 1,788.

How to lower your risk of cancer

If smoking rates decreased to 5% of the population by 2035, there will be 1,000 fewer cancer cases due to smoking compared to what is projected. Similarly, it  has been projected that  283 cases of cancer could be avoided by 2035 if the percentage of people who are overweight/obese is reduced by just 5%.

Other ways to decrease your risk of cancer include eating healthily, being physically active and reducing alcohol consumption.