Bowel cancer rates rising among younger adults

The incidence of bowel cancer is increasing among under 50s in Europe and other high-income countries around the world, two studies have confirmed.

The studies found that both colon and rectal cancer, collectively referred to as bowel cancer, have become significantly more common among under 50s. 

One of the studies, published in the journal Gut, looked at data from large population registries from 20 European countries. It found that the numbers of under 50s diagnosed with bowel cancer had increased from 1990 to 2016, from 0.8 to 2.3 cases per 100,000 people. Interestingly, the sharpest increases came between 2004 and 2016, with the 20-29 age group seeing a 7.9 percent increase in cases per year.

The second study, published in the Lancet Gastroenterology & Hepatology, looked at population registries from 21 countries, including the UK, Ireland, Australia and Canada, from when records began in those countries up to 2014. It revealed similar trends – in the UK it found 1.8 percent and 1.4 percent increases in colon and rectal cancer cases respectively in under 50s between 1995 and 2014. 

Dr Marzieh Araghi, lead author of the latter study, from International Agency for Research on Cancer in Lyon, France, said the findings highlighted the need for changes in screening. 'While population-based screening in people under 50 years old is not considered to be cost-effective due to relatively low incidence numbers, family history could help to identify younger people at high risk of genetic susceptibility to colorectal cancer, for further assessment,' Dr Araghi said.

The authors of both papers suggest further research is required to uncover the causes of this increase. One suggestion is that it is linked to the increasing prevalence of obesity and other health issues. 

Stephen Duffy, professor of cancer screening at Queen Mary University of London, said: 'Both papers suggest that sedentary lifestyles, overweight and dietary factors may be partly responsible for this [increase]. This is almost certainly the case, but it is probably not the whole story.'

Some experts have called for the screening age to be lowered to 45, in line with recommendations made by the American Cancer Society in 2018. In many parts of Europe the screening age is currently 50 or upwards. Others argue that starting screening earlier would not be cost effective. 

'It is probably too early to change policy, since despite the recent increases, the incidence in people under age 50 remains very low in absolute terms,' Professor Duffy concluded. 'What is reassuring is that while incidence is rising, mortality from the disease is falling, probably due to a combination of earlier diagnosis and improved treatment.'