British men are twice as likely to get bowel cancer today as they were in the mid-1970s, research has shown.
The odds of them developing the disease in their lifetime have increased from one in 29 to one in 15. For women, bowel cancer risk has risen by a quarter from one in 26 to one in 19.
In 2008 there were around 21,500 bowel cancers diagnosed in men compared with around 11,800 in 1975, according to new figures from Cancer Research UK.
There were around 17,400 cases of bowl cancer in British women in 2008 compared with 13,500 in 1975.
But while bowel cancer rates have gone up since the 1970s, so have survival times. Half of all patients diagnosed with the disease today survive for at least 10 years, double the number who would have lived that long in the early '70s.
Cancer Research UK epidemiologist Professor Peter Sasieni, who produced the figures published in the British Journal of Cancer, said: "As people are living longer the numbers getting cancer have increased and the lifetime risk of developing bowel cancer has gone up.
"Lifetime risk is a complex issue but it allows us to estimate the sheer number of people who will develop cancer by predicting the chance of getting the disease between birth and death based on today's cancer incidence rates and death rates from cancer and other causes.
"For some cancers - including bowel - the risk of cancer in the next 10 years will be much higher for people in their 50s and 60s. But if someone reaches their late 70s and hasn't yet developed the disease then their risk of getting it during the rest of their lifetime is lower than their risk at birth."
Sara Hiom, director of health information at Cancer Research UK, said: "An ageing population as well as changes in lifestyle have both led to more people developing cancer than a generation ago.
"But even though the chances of getting the disease have increased in the population there are many ways that people can cut their own risk. You can reduce your risk of bowel cancer by keeping a healthy weight, being physically active, eating a healthy diet that's high in fibre and low in red and processed meat, cutting down on alcohol and not smoking. It's also important to take up the opportunity to take part in bowel screening when invited."