What is the probability of developing cancer?

Image: Die Cast by Strep72, CC licenseOne in two of us will develop cancer at some point over the course of lifetime. This is the result of a recent study that was published recently in the British Journal of Cancer (1). Epidemiologists from Queen Mary’s University of London, UK, estimated the lifetime risk of developing cancer in the UK using data from the Office for National Statistics and from relevant cancer registries.

The lifetime risk of developing cancer is an artificial construct obtained by applying the estimated current age–specific cancer incidence rates and the overall mortality rates to a group of people that was born in a particular year. The authors compared the lifetime risk of developing cancer for those born in 1930 with those born in 1960. They showed that for men, the risk has moved from 38.5% for men born in 1930 to 53.5% for men born in 1960. For women, the change is similar, with an increase from 36.7% for women born in 1930 to 47.5% for women born in 1960.

It is interesting to evaluate the causes that drove this drastic increase. First of all, we are an aging population whose longevity is steadily increasing. The chances to develop a cancer during life increase because individuals live longer, and accumulate more time to develop a tumour. In addition, major changes in the incidence of specific tumours occurred in the period under evaluation.

In women, smoking habits steadily increased after World War II, and this continuing trend determined higher incidence rates of lung cancer and other tobacco-related cancers. In parallel, lifestyle changes have contributed to an increase of breast cancer rates, with women having fewer children at later ages, and an increasing prevalence of obesity. In men, the increase of prostate cancer rates is undoubtedly related to an ascertainment bias, with more use of prostate-specific antigen testing and earlier staging of prostate cancer. Last, the increase observed for colorectal cancer may have been driven by a combination of factors including increased consumption of red meat, decreased physical activity and obesity.

That people of the 1960 generation have a 1 in 2 lifetime risk of developing cancer has important implications for all those involved in public health, and particularly for citizens, whose awareness in relation to chronic diseases, and cancer in particular, has continuously increased during recent years. The trends observed in the study seem to be expected to increase further. It will be of interest to follow whether the growth of individuals’ awareness will contribute to an uptake of strategies to help reduce the probability of developing cancer during lifetime.

 

(1) Ahmad AS, Ormiston-Smith N, Sasieni PD. Trends in the lifetime risk of developing cancer in Great Britain: comparison of risk for those born from 1930 to 1960. Br J Cancer. 2015 Mar;112(5):943-7.

Pietro Ferrari

Pietro Ferrari

Pietro Ferrari is a statistician working in the Nutritional Epidemiology Group at the IARC in Lyon, France. He has been long involved in the EPIC study, and his research covers aspects related to Nutritional Epidemiology. These include evaluations of dietary exposure misclassification, technique for bias correction in exposure disease models, competing risks modelling, analysis of complex sets of data involving dietary, lifestyle and biomarker measurements, modelling of metabolomics and epigenetic data.
Pietro Ferrari

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