Screening for the presence of polyps and removing them before they become cancerous is an important part of bowel cancer prevention, particularly in people who at very high risk of developing the disease.
About bowel cancer
Bowel cancer is the second biggest cause of cancer deaths in the UK and will affect around 1 in 17 people at some time in their life. It can occur in younger people but becomes much more common in the over 60s. As many as 90% of bowel cancers can be successfully treated if they are detected early enough, even in older patients.
Screening for bowel cancer
The first stage of bowel cancer screening in the NHS is the faecal occult blood test (FOB). This is used to detect any signs of blood in the faeces that may be the result of cancerous growths in the bowel.
This is available on the NHS for people aged 65 to 75. Around 98% of people will have a normal result from their FOB, and the remaining 2% will be advised to have further examinations. A digital rectal exam (DRE) may also be performed, in which your doctor will insert a finger gently into your rectum to feel for any lumps associated with rectal cancer.
If your FOB test or DRE test raise suspicion of colorectal cancer, you will be advised to have a colonoscopy, so that the inside of your large intestine can be examined in detail. If this happens to you, you should not panic, as only one in ten people who are referred for a colonoscopy following an irregular FOB test are diagnosed with cancer.
For some patients, the age cut-offs for FOB screening and flexible sigmoidoscopy within the NHS means they cannot access bowel cancer screening at a younger age. If you are worried about bowel cancer, if it seems to run in your family or you have even vague symptoms, it is worth getting checked out.
Dr Wilson can perform a private colonoscopy or flexible sigmoidoscopy (which examines less of the large bowel than a colonoscopy but is more easily tolerated). Many patients decide to book a colonoscopy and pay for it themselves, just for peace of mind.
Colonoscopy cancer screening
Colonoscopy uses a long flexible tube, with a light and camera on the end, to examine the full length of your large bowel. This allows Dr Wilson to examine the lining of the bowel for polyps or other abnormal regions, and to take small tissue samples, called biopsies, for examination in the laboratory.
A colonoscopy is the most thorough way to check for bowel cancer, since it allows your doctor to directly examine the entire length of your large bowel. There is a small chance that cancer could be missed, for example if the bowel is not completely empty or if the tube cannot reach the full length of the bowel. However, colonoscopy will detect bowel cancer in more than 95% of cases.
Dr Ana Wilson explains more about a colonoscopy in this video, produced by Macmillan Cancer Support.
Polyp removal using colonoscopy
Polyps are small growths in the lining of the bowel. Some of these are pre-cancerous or cancerous, while most are non-cancerous. As many as one in five people have polyps and most will never know they have them. However, if left untreated, polyps in the large bowel can develop into cancer, so they will usually be removed as a matter of course during your colonoscopy.
If you have many polyps, you may need a follow-up colonoscopy to complete their removal.
The benefits of regular bowel cancer screening
Colonoscopy is not only a diagnostic test for when colorectal cancer is suspected, it can also be used as a proactive, preventative measure. Often, colorectal cancer will not show any significant signs or symptoms until it is well advanced, by which time it is harder to treat and the potential outcomes are much less favourable.
Proactively screening for colorectal cancer, especially after the age of 50, gives you the best chance of having your bowel cancer identified as early as possible, significantly increasing the chances of successful treatment. Depending on the findings of the colonoscopy further surveillance colonoscopies may be recommended. This will depend on the number and size of polyps found during the initial procedure as well as your personal and family history of polyps and/or colorectal cancer.