Monday October 4 2010
Cancers can develop inside clumps of cells known as polyps
“PM David Cameron has announced £60m over the next four years to introduce the latest cancer screening technology,” reported BBC News. It said that better bowel cancer screening using a technique called flexible sigmoidoscopy could save 3,000 lives a year.
The technique is being considered for inclusion as part of the existing screening programme, which began in 2006.
The BBC reported that health secretary Andrew Lansley said pilot schemes will begin next spring, subject to approval by the UK National Screening Committee.
Screening plays an important part in the fight against bowel cancer because the earlier the cancer is diagnosed the greater the chance of achieving a complete cure.
What is sigmoidoscopy?
A sigmoidoscopy uses a device called a sigmoidoscope, a thin, flexible tube that is attached to a small camera and light. The tube is inserted into your rectum and then up into your bowel. The camera relays images to a monitor, which allows doctors to check for any abnormal areas within the rectum or lower bowel that could be the result of cancer.
A sigmoidoscopy can also remove small samples of suspected cancerous tissue so that they can be tested in a laboratory.
The technique is already available in the UK, but is not currently used for screening purposes. At present, it is given to people with symptoms that already suggest bowel cancer, or for people who have been referred for the test by their GP or specialist.
Why is it being added to the screening programme?
A large, 16-year randomised controlled trial published earlier this year found that screening with sigmoidoscopy could greatly increase the diagnosis of cancer and reduce deaths from colorectal cancer.
The trial found that people invited for one-off sigmoidoscopy had a 23% reduction in the risk of being diagnosed with colorectal cancer. They also had a 31% reduction in the risk of death from colorectal cancer compared to a control group that was not invited for sigmoidoscopy.
What were the results of the trial?
Of the people invited for screening, there were 114 cases of colorectal cancer diagnosed per 100,000 person-years of follow-up, compared to 149 cases per 100,000 person-years in the control group. Among the people invited for screening, there were 30 deaths from colorectal cancer per 100,000 person-years of follow-up, compared to 44 deaths from colorectal cancer per 100,000 person-years in the control group.
When the researchers looked just at the people who actually went for flexible sigmoidoscopy (that is, excluding the people who were invited but did not attend), they saw a 33% reduction in the risk of diagnosis with colorectal cancer, and a 43% reduction in the risk of death from colorectal cancer compared to the controls.
Based on their results, the researchers estimated that 191 people would need to be screened to prevent one diagnosis of colorectal cancer, and 489 screened to prevent one death from colorectal cancer over about 11 years.
What does the current screening programme involve?
The current programme uses a test called a faecal occult blood test, which looks for blood in stools. The test can be done at home and the sample sent to a laboratory for assessment. People who have abnormal results on this test are invited for an endoscopy (colonoscopy) to investigate further.
A colonoscopy also involves inserting a flexible tube with a camera into the colon via the rectum to look for any abnormalities and can look at the upper and lower parts of the colon. It is usually done with sedation and painkillers to reduce any discomfort. The procedure is done on an outpatient basis, and takes about an hour.
This type of screening is currently offered every two years to all people aged 60 to 69 years old. The programme is being extended to people up to 75 years old.
Who is the new screening technique aimed at?
The existing bowel cancer-screening programme is aimed at people aged 60 to 75 years old, but it is not yet clear whether this will be the same target group for sigmoidoscopy.
The trial published earlier this year was designed to investigate the effects of screening for adults aged 55 to 64 with no history of bowel disease or cancer, no symptoms suggestive of bowel cancer, no family history of bowel cancer, and who had not had a sigmoidoscopy or colonoscopy in the past three years.
How long does the procedure take?
The procedure usually takes between 10 and 15 minutes. A sigmoidoscopy is not usually painful, but it can feel slightly uncomfortable. As the tube is only inserted into the lower part of the colon, sedatives or anaesthetics are not usually needed. Most people are able to go home after the examination.
When is it likely to be added to the programme?
Health secretary Andrew Lansley has said that pilot schemes using sigmoidoscopy will start in 2011, subject to the approval of the National Screening Committee. The programme would be rolled out over four years.
Professor Julietta Patnick CBE, director of the NHS Cancer Screening Programmes, said: “The addition of flexible sigmoidoscopy will allow us to build on the great success of the existing bowel cancer screening programme. If recommended, we will be busy over the next few months developing the processes and QA [quality assurance] procedures that will be needed in order to deliver this new service safely and effectively.”
How common is bowel cancer?
In England, bowel cancer is the third most common type of cancer, and an estimated 30,800 new cases are diagnosed each year.
About 14,000 cases of bowel cancer are diagnosed in women, making it the second most common cancer in women after breast cancer. The remaining 16,800 cases of bowel cancer are diagnosed in men, making it the third most common cancer in men after prostate and lung cancer.
Approximately 80% of bowel cancer cases develop in people who are 60 years old or more. Two thirds of bowel cancers develop in the colon, and the remaining third develops in the rectum. In England, there are an estimated 13,000 deaths as a result of bowel cancer each year.
What are the risk factors for bowel cancer?
The risk factors for bowel cancer include:
- a diet high in red and processed meat, and low in fibre
- being obese
- being physically inactive
- having a bowel condition, such as Crohn’s disease or ulcerative colitis
- having a family history of bowel cancer
- alcohol misuse
What are the signs and symptoms of bowel cancer?
The initial symptoms of bowel cancer include:
- blood in your stools (faeces) and/or bleeding from your rectum
- a change to your normal bowel habits that persists for more than six weeks, such as diarrhoea, constipation or passing stools more frequently than usual
- abdominal pain
- unexplained weight loss
As bowel cancer progresses, it can sometimes cause bleeding inside the bowel, which eventually causes a deficiency of red blood cells in the body. This is known as anaemia.
Symptoms of anaemia include:
In some cases, bowel cancer can cause an obstruction in the bowel. Symptoms of a bowel obstruction include:
- a feeling of bloating, usually around the navel (belly button)
- abdominal pain
When to seek medical advice
Always contact your GP if you have any of the symptoms listed above. While the symptoms are unlikely to be the result of bowel cancer, these types of symptoms always need to be investigated further.