A new study, led by Cancer Research UK, has found that more than 135,000 cases of cancer could be prevented in the UK each year, largely through lifestyle changes. This corresponds to nearly 4 in 10 cases[i]. Analyses like this have been done before, but the new research uses all the latest available data and evidence to give more accurate estimates[ii].
There are many factors that may contribute to cancer development, and they can be broadly classified as those people can control, and those they cannot. Factors that cannot be controlled include inherited genes and random genetic changes (bad luck), and factors that can be controlled include exposures to agents known to be carcinogenic.
In the study, population attributable fractions (PAFs) were calculated for combinations of risk factor and cancer type where there is some evidence of causation, e.g. smoking and lung cancer, and obesity and bowel cancer. The increased risks of exposure were calculated by comparing the risk of exposed people developing the cancer to the risk of unexposed people, and the numbers of people affected were determined by considering the numbers of people exposed to each risk factor.
Tobacco smoking contributed by far the largest proportion of attributable cancers, followed by being overweight or obese. Other factors that contributed to the burden of cancer in the UK were diet, exposure to the sun, exposure to substances at work, infections and alcohol consumption. Rick factors that contribute the most cases to the overall cancer burden are:
- Those with the highest relative risks associated with exposure;
- Those with the highest exposure prevalence in the population;
- Those with the largest number of associated cancer types; and
- Combinations of the above.
There were 10 types of cancer for which more than 70% of cases were attributable to known risk factors. These include lung cancer and melanoma skin cancer, which are 2 of the 5 most common cancer types in the UK. Overall, 37.7% of cancer cases in the UK could be attributed to known risk factors. The proportion was slightly higher in males than females, with attributable cancers comprising 38.6% and 36.4% of cases, respectively. In the UK, 9,087 (5.0%) cancers were attributable to occupation and 7,025 (3.8%) were attributable to ultraviolet radiation.
The researchers hope that their data will be used to inform prevention efforts and reduce the population-level burden of cancer in the UK.
[i] Brown, K. F. et al. The fraction of cancer attributable to modifiable risk factors in England, Wales, Scotland, Northern Ireland, and the United Kingdom in 2015. British Journal of Cancer 1 (2018). doi:10.1038/s41416-018-0029-6 https://www.nature.com/articles/s41416-018-0029-6 (Accessed 5 April 2018)
[ii] New calculations confirm lifestyle changes could prevent 4 in 10 cancer cases. Cancer Research UK Science Blog. http://scienceblog.cancerresearchuk.org/2018/03/23/new-calculations-confirm-lifestyle-changes-could-prevent-4-in-10-cancer-cases/ (Accessed 5 April 2018)