A new report, published by the National Cancer Registry of Ireland (NCRI) and co-funded by the Irish Cancer Society, shows that in Ireland, about 6,200 newly diagnosed cancer cases in 2016 alone were attributable to the 11 modifiable risk factors examined.
The report indicates that, just among these factors, 29 per cent of cancer incidence in Ireland was potentially preventable. This relates to 3/10 of all invasive cancers (excluding non-melanoma skin cancer) cases being attributable specifically to the sum of the risk factors examined.
This is the first analysis by the NCRI on the proportion of cancer cases attributable to modifiable risk factors and thus potentially preventable.
NCRI data on the number of cancer cases in 2016 was utilised for this report. Data was also compiled from a variety of sources to determine both the extent to which the Irish population are exposed to each risk factor and the likelihood of being diagnosed with cancer as a result of the exposure. All of this information was inputted to formulae to calculate the percentages and numbers of cancer cases attributable to 11 risk factors.
Smoking, overweight and obesity, and infections were the top three modifiable risk factors for cancer in Ireland, together accounting for about 21 per cent of all cancers. These risk factors need to continue to be targeted by public health representatives and policymakers.
At about 2,800 diagnoses in 2016, 13 per cent or about one-eighth of cancer cases were attributable to smoking, including passive smoking. In 2035, assuming these risk estimates continue to apply, it is estimated that about 4,700 cases of invasive cancer per year will be attributable to smoking.
Lung cancer had the highest number of cases attributable to modifiable risk factors in both males and females, followed by colon cancer in males and breast cancer in females.
Over a ten-year period ending in 2035, it is estimated that a cumulative total of 66,000 cancer cases (2026-2035) will be attributable to three of those factors alone — smoking, overweight and obesity, and alcohol consumption.
“It is important to note that the figure of 29 per cent of cancers in Ireland being potentially preventable is an underestimate,” according to the NCRI.
“For example, the risk associated with occupation was not accounted for here and should be examined in future research. In the UK, 4 per cent of cancer cases were attributable to occupation-related risk. Additionally, everyday exposure to ultra-violet radiation was not included, only sunburn history and sunbed usage, while some additional cancers, with less conclusive evidence on risk factors, may also be preventable.”
Commenting on the report’s findings, Prof Kerri Clough, Director of the NCRI, said: “This report on the burden of cancer attributable to modifiable risk factors in Ireland will aid decisions on priorities for cancer control initiatives. This is the first time that the impact of multiple lifestyle or other modifiable factors on cancer risk has been assessed in Ireland. This report builds on previous NCRI reports on projections of cancer incidence and reinforces the important role that cancer prevention strategies can have in ensuring that projected increases in cancer incidence are not realised.”
Dr Colette O’Neill, epidemiologist at the Registry and lead author on the report, noted: “The key finding is that 29 per cent of cancer incidence in Ireland (6,200 cancer cases in 2016 alone) was attributable to the 11 modifiable risk factors examined, and thus potentially preventable. These figures could translate into tens thousands of cancer cases over the coming years and decades, depending on the timelines involved and how successful cancer prevention strategies and interventions are in the meantime.”