According to research conducted by the University of Western Australia, people who have had a desk job for more than 10 years are at almost double the risk of getting bowel cancer. The scientists have also found that even office workers who take regular exercise will still be twice as likely to get a tumour as similarly active people who have less sedentary jobs.
Every year almost 40,000 people are diagnosed with bowel cancer, while more than 16,000 die. About 70 per cent survive for at least a year past diagnosis, while half survive to at least five years.
It is well established that the main lifestyle risk factors are diets high in fat and red meat, drinking a lot of alcohol, and not taking enough exercise. Genes also play a part.
However, now Australian researchers have shown that long periods of physical inactivity during the working day could also significantly increase the risk, even among those who exercise a lot in their free time.
The team, from the University of Western Australia, found that people who spent more than 10 years in sedentary jobs were almost twice as likely (94 per cent) to have developed a tumour in the area of the lower bowel called the distal colon. They were also 44 per cent more likely to have developed rectum cancer.
There are almost 13,000 distal colon cancer cases a year in Britain, and about 14,500 rectum cancers, according to the charity Bowel Cancer UK.
The results, published in the American Journal of Epidemiology, compared 918 people with bowel cancer with 1,021 cancer-free volunteers. They were quizzed on their job history, lifestyles and levels of physical activity.
Researchers also found sedentary working patterns increased the chances of cancer of the rectum by 44 per cent over a ten year period.
The researchers said their findings suggest no amount of leisure time activity can offset the harm done from long periods of sitting down on the job.
In a report on their findings they said: ‘We found those who spent the most time in sedentary work had a risk of distal colon cancer that was twice that of those who spent the most time in a job requiring light activity.
‘Even a high level of vigorous recreational physical activity did not modify the effect of sedentary work.’ And they warned: ‘The findings have occupational health implications, given that advances in technology have led to increasing amounts of sedentary behaviour at work.’ Sitting down on the job is thought to lead to increased blood sugar levels and damage insulin production, both of which have been linked with the development of bowel cancer.
It could also be that it leads to inflammation deep inside the body, another known risk factor for tumours, researchers said.
Dr Claire Knight, health information officer at Cancer Research UK, said the findings back up other studies on physical inactivity and cancer, but warned the findings need to be replicated in larger studies.
