Bowel cancer is rising among young people in the UK and Europe, researchers have warned.
Across Europe, the rate of new cases of colon cancer among people aged 20 to 39 has risen by 7.4% each year between 2008 and 2016, with incidence of rectal cancer also increasing.
The research, from the Erasmus medical centre in Rotterdam, included data from national cancer registries of 20 European countries, including the UK, Norway, Slovenia and Germany.
In 65% of countries colorectal cancer incidence rose in young people, while in 30% it remained steady and in 5% it declined.
Fanny Vuik, of the Erasmus medical centre in Rotterdam, said there was a decrease in incidence for the older population because most of the European countries have a colorectal cancer screening programme, enabling them to detect cancer at an earlier stage.
Despite this, the researchers said they do not recommend screening be extended to younger individuals.
Although rates have risen, the absolute risk remains low. For young people between the age of 20 and 39, the incidence increased from 2.2 to 4.9 per 100,000 persons between 1990 and 2016.
Prof Scott Montgomery, of Örebro University hospital in Sweden and University College London, who was not involved in the work, told the Guardian the most likely factor was rising obesity.
“The thing about cancer is it has a long natural history: you have many years of exposure that increases your risk, so many years of unhealthy diet and inflammation associated with obesity will just build that cancer risk as people age,” he said.
Katie Patrick, from Cancer Research UK, said the findings reflect the situation in Britain where the number of people between 25 and 49 who are diagnosed with bowel cancer has increased over the past two decades.
According to recent figures, bowel cancer is the second most common cause of cancer death in the UK, with about 16,000 deaths a year.
More than half of bowel cancer cases are thought to be preventable.