Bowel cancer affects the large bowel and the rectum and is common in the Western world.
In Scotland, about 3500 people will be diagnosed with the disease every year and about 1700 will die in that period.
Although the precise causes of bowel cancer are still not clear, we have learned a lot in recent years. In a small proportion of cases (around five per cent) it’s directly inherited but, in the main, the risk factors are lack of exercise, being overweight, eating large amounts of red and processed meat, alcohol and lack of sufficient dietary fibre.
Sadly, Scotland has one of the highest incidences of bowel cancer in the world and the most important thing we can do to avoid developing the disease is to modify our lifestyle.
It is also important to appreciate that if caught at an early stage bowel cancer is a curable disease – more than can be said for other chronic diseases such as chronic bronchitis or peripheral vascular disease. Given that it’s unrealistic to expect to prevent all cases of bowel cancer, our approach to treating the disease must be early diagnosis, as once the cancer has spread beyond the bowel itself it is much harder to treat.
It’s tempting to highlight the symptoms of bowel cancer and to recommend rapid investigation but there’s a problem with this approach. The symptoms of bowel cancer can consist of bleeding from the back passage, change of bowel habit particularly to looser bowel motions, abdominal pain and the symptoms of anaemia (tiredness, breathlessness and dizziness).
However, these are extremely common symptoms and are more often than not caused by simple non-life threatening conditions. Indeed, when they are caused by bowel cancer they indicate relatively advanced disease.
What then can we do to give the people of Scotland the best opportunity of early diagnosis of bowel cancer? At the present time, the best answer is to encourage everyone to participate in the Bowel Screening Programme.
In Scotland, between the ages of 50 and 74, everyone is invited to participate in screening every two years by returning small samples to the central screening laboratory in Dundee, where it is analysed for traces of blood. If blood is identified, a colonoscopy is offered.
This form of screening is by no means perfect; not all bowel cancers will be detected and about half of the people with a positive test will have a normal colonoscopy. However, recent research has shown that people who participate in bowel screening have their risk of dying from bowel cancer reduced by about one-third and this is due to the fact that the majority of cancers diagnosed by screening are at an early stage.
In addition, a substantial number of people will be found to have bowel polyps that can be removed at the time of colonoscopy and this has the potential to prevent bowel cancer from developing.
Taking part in screening is a matter of individual choice and a little under half of the people offered screening choose not to do it. The simple fact remains: the larger the number of people that screen, the fewer will die from the disease.
Those who work in the area of bowel cancer screening are very aware of its limitations, and in Scotland there is an active programme of research and development to improve the process by making it more acceptable and more accurate.
Scotland was the first country in the world to have a fully implemented national bowel screening programme and that is something we can be proud of. It has already had a measurable impact on the disease, and if more people participate and if we can improve the screening processes, we will go a long way to removing bowel cancer from the list of major causes of death in this country.
• Professor Bob Steele is director of the Scottish Colorectal Cancer Screening Programme.