Cancer used to be seen as part of ageing: something that mainly afflicted people over the age of 60 or 70. But although it is still true that the majority of new cancer diagnoses affect the over-70s, the pattern is changing in subtle ways. Some cancers are increasingly found in younger people.

Take colorectal (bowel) cancer: while rates have declined in those over 60, data shows a sharp increase in many developed countries among people under 50, in what’s called early-onset disease.

This isn’t just due to wider screening or better diagnosis, and it isn’t only found in one particular country or community. In England, the NHS bowel cancer screening programme covers people aged 50-74 by inviting them for a free screening every two years. However, this age range excludes younger people, who are usually only diagnosed at a late stage when the cancer has spread and they are symptomatic.

What’s causing the rise in young people? We can rule out genetics: it’s estimated that 75% of cases are in people with no previous family history or known genetic predisposition. Scientists have started to look at environmental factors tied to the increase in colon cancer since the 1960s, with each generation more likely to get cancer than the previous one.