At a glance: Bowel cancer – screening and prevention
In Germany, you can have bowel cancer screening if you are 50 years of age or older. It is your personal decision whether you take part and which examination you choose. In this text we will give you information about the advantages and disadvantages of the different tests and help you in making a decision.
How can I benefit from screening?
Screening tests aim to detect bowel cancer or preliminary stages of bowel cancer before they cause any symptoms. This is based on the idea that if bowel cancer is treated at an early stage, treatment will be more successful and involve less harm or discomfort. In an endoscopy of the bowel, bowel polyps – non-cancerous preliminary stages of bowel cancer – can be removed during the examination. The aim of removing bowel polyps is to prevent these polyps from possibly developing into bowel cancer.
What are the options for bowel cancer screening?
In Germany, bowel cancer screening tests are meant for people between the ages of 50 and 75 who do not have a particularly high risk of bowel cancer. Statutory health insurance funds pay for the following two methods that members can choose between:
- Test for hidden blood in the stool (chemical stool test)
- Colonoscopy (endoscopy of the entire large bowel)
Another option is sigmoidoscopy, an endoscopic examination of the lower part of the bowel. As of now statutory health insurance funds in Germany do not pay for this examination when it is used for screening. You can find more information about which screening tests are covered by statutory insurance funds here.
A stool test looks for traces of blood in the stool that cannot be seen by the naked eye and which may be signs of bowel cancer or advanced bowel polyps. The advantage of this test is that it is easy to do and has no direct adverse effects. But it is not very reliable: Many suspicious test results later turn out to be false alarms. And the test overlooks many tumors, too. Because the stool test is not suitable for detecting bowel cancer and polyps with certainty, you can have an endoscopy of the bowel if the test finds traces of blood in the stool. Only by doing this can you benefit from a stool test.
Trials show that screening by stool test can lower the risk of dying of bowel cancer if the test is done every two years over a period of at least ten years. Trials show the following results:
- Out of 1,000 people who did not do the test, about 10 died of bowel cancer.
- Out of 1,000 people who did the test regularly, about 8 to 9 died of bowel cancer.
This means that the screening saved 1 to 2 out of 1,000 people from dying of bowel cancer.
Because the stool test often produces false alarms, it can also worry people unnecessarily. On the other hand, the test also fails to detect some cancerous tumors. An endoscopy of the bowel following a stool test can have adverse effects.
In Germany, members of a statutory health insurance fund between the ages of 50 and 54 are entitled to have a stool test once a year. After the age of 55, they can have a stool test every two years.
In Germany, instead of having a stool test you can also have two colonoscopies (or coloscopies) over the age of 55 years. At least ten years must have passed between the two colonoscopies.
In a colonoscopy, the doctor endoscopically examines the entire large bowel for bowel polyps and tissue suspected of being cancer. This is done with a colonoscope (or coloscope), a flexible tube with a small light and a camera that is guided into the bowel. In theory, this examination can find most bowel polyps and cancerous tumors. It is a more involved kind of bowel cancer screening test, however.
Before you have a colonoscopy, your bowel has to be completely empty. It is helpful to avoid eating foods that are difficult to digest in the days leading up to the examination. There are different ways to prepare for the examination, but it is usually necessary not to eat any solid food at all in the 24 hours before the colonoscopy. On the day before the procedure, and sometimes on the day itself, you will drink a laxative and a lot of fluid, until only a clear liquid comes out when you go to the toilet. Your doctor will tell you more details.
Complications of a colonoscopy include bleeding and problems with the heart and circulation. About 2 to 3 out of 1,000 people having a colonoscopy have one of these complications. Intestinal perforation, a very serious complication, can also happen in very rare cases.
There has not been enough good research on colonoscopy, which makes it difficult to weigh its advantages and disadvantages.
The best evidence of a benefit for colonoscopy comes from trials on sigmoidoscopy, where the last 60 centimeters of the large bowel are examined with an endoscope for polyps and tissue suspected of being cancer. About two thirds of all cancerous tumors grow in this part of the bowel.
A large British trial with more than 170,000 men and women between the ages of 55 and 64 showed that a single sigmoidoscopy examination can effectively prevent bowel cancer. After 11 years, the researchers found the following results:
- In about 5 out of 1,000 people who were offered a sigmoidoscopy could be prevented from getting bowel cancer because advanced polyps were removed.
- In about 2 out of 1,000 people who were offered a sigmoidoscopy, bowel cancer was prevented.
You can find further information on sigmoidoscopy in our more in-depth article.
Other methods: Immunological stool tests
Some doctors offer immunological tests for bowel cancer screening. Like chemical stool tests, they also look for hidden blood in the stool. Immunological tests look for certain protein particles in hemoglobin, a protein in the red blood cells. There has not been any research yet on whether this test can lower the risk of dying from bowel cancer like the chemical stool test can. Statutory health insurance funds in Germany do not pay for immunological tests, so they have to be paid for out-of-pocket.
Making a decision
There is no need to make your decision under pressure. You can take your time to find out whether or not you would like to have a screening test.
You should also bear in mind that the numbers given here refer to people with an average risk. People who have parents, children or siblings with bowel cancer or people who have a chronic inflammatory disease of the bowel like ulcerative colitis have a higher risk of getting bowel cancer. They might therefore be more likely to benefit from a screening test.
You can find more in-depth information on bowel cancer screening and prevention as well as the sources of this information in our article.
Author: Institute for Quality and Efficiency in Health Care (IQWiG)
Next planned update: December 2014. You can find out more about how our health information is updated here.