Male bowel cancer risk doubles in 30 years
In 1975, one in 29 men in Britain were estimated to go on to develop the disease at some point in their lifetime. But that figure has now increased to around one in 15.
Women's lifetime risk of bowel cancer has also risen by more than a quarter, from one in 26 to one in 19 during the same period, according to Cancer Research UK.
The ageing population, along with lifestyle factors such as poor diet, obesity and alcohol use, have helped boost the number of people struck with cancer.
The charity said other figures showed that men were more at risk of getting cancer generally than women, with 42.2 per cent developing the disease compared to 38.8 per cent of women.
But improved treatments and better diagnosis now mean many more people were surviving than in the past, experts said. Professor Peter Sasieni, researcher and epidemiologist, 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 cancer, the risk of cancer in the next ten 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."
In 2008 there were about 21,500 cases of bowel cancer in British men, up from 11,800 in 1975. In women cases increased from 13,500 to 17,400 over the same period.
In Scotland about 4,000 cases of the disease are now diagnosed each year. But while rates have been rising, figures also show that half of all patients diagnosed with bowel cancer now survive the disease for at least ten years - compared to just 23 per cent in the early 1970s.
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."
A Scottish Government spokesman said: "Progress is being made in the treatment of bowel cancer in Scotland and a screening programme has been introduced to help identify the disease early.
"But bowel cancer remains one of the most frequently diagnosed cancers in Scotland, and we want to do even more to improve survival rates."