Bowel (or colorectal / colon) cancer is the second most common cancer in the United Kingdom, with over 30,000 new cases and almost 20,000 deaths each year. 93% of these deaths occur over the age of 55 and the incidence increases with age with an average lifetime risk of 1 in 25.
The risk is increased if there is a family history of colorectal polyps or cancer, and is still higher if there is a personal history of breast, uterine or ovarian cancer. Risk is also higher for people with a history of extensive inflammatory bowel disease, such as ulcerative or Crohn's colitis.
Rectal bleeding and change of bowel habit are the most common symptoms, though these are common symptoms of other diseases. The key is to see if these symptoms persist over a number of weeks.
Other symptoms include persistent, intense abdominal pain, unexplained anaemia and abdominal lumps.
If you have any of these symptoms, make an appointment with your GP who will refer you to a specialist if appropriate.
In 2006, the government plans to make available a limited form of screening, based on stool testing for men and women over 60 years old.
However, in the United States screening from the age of 50 by a combination of annual faecal occult blood testing (stool testing) and flexible sigmoidoscopy every 5 years at age 50 or older is recognised best practice. This service is available at The Priory Hospital in Birmingham, with prices starting from £75.
Many polyps and cancers of the colon and rectum do not produce symptoms until they become fairly large. Screening involves one or more tests performed to identify whether a person with no symptoms has a disease or condition that may lead to colorectal cancer. The aim of screening is to identify the potential for the disease or the condition early when it is easier to prevent or cure.
Colorectal cancer is known as a "silent" disease, because the disease usually presents with non-specific symptoms which may be ignored by the patient. Many people do not develop symptoms, such as bleeding or abdominal pain until the cancer is difficult to cure. In patients who develop symptoms from a colorectal cancer the cure rate is only about 50%. On the other hand, if colorectal cancer is found and treated at an early stage, before symptoms develop, the opportunity to cure is 80% or better. Most colon cancers start as non-cancerous growths called polyps. If the polyps are removed, then colorectal cancers may be prevented and major surgery can usually be avoided. The development of polyps and cancers is a slow process, taking 10 years on average.
In the UK there are currently no standardised screening protocols or recommendations. The choice for population screening lies between biennial faecal occult blood testing from the age of 50 or a one-off flexible sigmoidoscopy performed between the ages of 55 and 64 years.
It is important to remember that not all tumours or polyps may be detected by these tests and if you develop any new or unexplained bowel symptoms you should consult your own GP for advice.
The simplest screening test for colorectal cancer is testing of the stool to detect tiny amounts of invisible blood; this is called faecal occult blood testing. This test has been available for many years, is inexpensive and very simple. Whilst it has been shown that colorectal cancer mortality can be reduced by 15% using this screening test, unfortunately it only detects cancer or polyps which are bleeding at the time of the test. The test cannot distinguish whether the blood in the faeces is caused by a tumour or a minor condition such as piles. A falsely positive result can also be caused by certain foods or drinks. If the test is positive a colonoscopy will be performed to determine the cause of bleeding. Only about 50% of cancers and 10% of polyps bleed enough to be detected by this test. Therefore, further screening is necessary for accurate detection of cancers and polyps.
Flexible sigmoidoscopy is a test which allows the doctor to look directly at the lining of the colon and rectum. During this test, which takes around 5 minutes in an operating theatre, the lining of the lower one-third of the colon and rectum can usually be seen. It is estimated that two thirds of all cancers and polyps are located in this portion of the lower intestine. Where polyps are found examination of the whole colon by colonoscopy may be advised. A full information leaflet on the procedure is available.
When a polyp or cancer is detected by flexible sigmoidoscopy, or if a person is at high risk to develop colorectal cancer, colonoscopy provides a safe, effective means of visually examining the full lining of the colon and rectum. Colonoscopy is used to diagnose colorectal problems and to perform biopsies and remove colonic and rectal polyps. Most colonoscopies are done on an outpatient basis with minimal inconvenience and discomfort. A full information leaflet on the procedure is available.
A barium enema is a type of x-ray of the colon. It is almost as good as a colonoscopy in detecting large tumours, but it is not as accurate for small tumours or polyps. The combination of barium enema and sigmoidoscopy is better than either test alone, but not as good as colonoscopy on its own.