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Bowel cancer

Bowel cancer (Large bowel and rectal cancer) is one of the most common cancers in the western world and in Denmark we have more than 4000 new cases each year.

Who gets bowel cancer?

Five percent of the population is affected by bowel cancer, i.e. about 1 in every 20 individuals. The risk of bowel cancer at some point in life is 5%. There is an equal distribution among men and women.

Is bowel cancer hereditary? Who is at risk?

Only a few cases - approx. 5% are hereditary. In most cases you cannot identify anything hereditary. Nevertheless we know that the risk increases if there are close family members who have had the disease (parents or siblings). If you have had intestinal polyps removed or have had chronic intestinal inflammation for more than 10 years, the risk also increases. Other diseases that may increase the risk for bowel cancer are cancer of the uterus, ovaries and cancer of the urinary tract.

What causes bowel cancer?

The greatest risk of having bowel cancer is increasing age. After age 45 the risk increases significantly, and the disease is most common among people older than 70 years of age.

The reason that age has an impact is likely because mutations accumulate in the mucosa with age: The mucosal lining of the colon and rectum exfoliates continuously and are usually replaced completely during 5 days (a significant portion of the stool is exfoliated cells). Thus there is an excessive activity in the mucosa with formation of new cells, which takes place by cell division. A result of these numerous cell divisions (10-15 billion daily) is approx. 25.000 cell division errors (mutations) in the bowel. Most are harmless and repaired by the body’s own DNA repair mechanisms. Some mutations, however, escape the body’s control system and accumulate quietly in the bowels cells. With age, these mutations can lead to polyp development and subsequent cancer.

We know that the diet is a risk factor, particularly high levels of beef and pork consumption increases the risk – not poultry and fish. It is probably the strong chemicals in our own digestive system, which contributes to initiate the process, especially bile acids and fatty acids produced in large quantities in order to digest meat.

Vegetarians get bowel cancer half as frequently as people who eat meat.

Statistically it is shown that there is a correlation between lack of exercise and development of bowel cancer. However, there is no agreement on the amount of exercise necessary to achieve a protective effect, but you should expect at least 30 minutes per today.

Aspirin (acetylsalicylic acid) protects against the development of bowel cancer, but also has significant side effects in terms of risk of gastritis, gastric ulcers and increased risk of bleeding (e.g. brain hemorrhage)

It is shown that individuals who take aspirin on a regular basis to prevent cardiovascular events only develop bowel cancer half as frequently as others. There is no agreement on the dose or for how long to take aspirin to achieve protection.

Vitamin D and Calcium
Both vitamin D and calcium supplements appear to protect against bowel cancer. In the majority of the western world, the daily intake is below the recommended amount. For vitamin D's case, there are very few foods that contain vitamin D in any significant quantity, and by far the largest amount of vitamin D is produced in the skin through the effects of sunlight. The lack of sunlight causes many people to have vitamin D deficiency, especially in countries where the sun doesn’t appear regularly on a consistent basis.

If you aren’t in the sun regularly, and don’t eat dairy products daily, you should take vitamin D / Calcium supplements, which are available over the counter at pharmacies.

Are there any preliminary stages of bowel cancer - and can they be removed?

Almost all cases (>95%) of bowel cancer arise in polyps, which gradually grow and become malignant, and finally set itself as a cancerous tumor on the inside of the intestine.


Intestinal Polyps, which almost never causes symptoms, are quite common and the incidence increases with age. 25% of 50 year olds has bowel polyps, 50% of 65 year olds has bowel polyps. Fortunately, not all polyps develop into cancer, but with larger polyps and higher numbers of polyps the risk is greater for developing cancer with time. By eliminating intestinal polyps, the risk of bowel cancer is minimized.

How do you examine for bowel cancer?

If there are symptoms that raise suspicion of bowel cancer, or you belong to high-risk-group, you should have an examination of the colon and rectum (colonoscopy). Contact the clinic and book a colonoscopy.

In 2014, Denmark will introduce a population-screening program for bowel cancer for people at age 50-75. The examination consists of stool testing for blood. If the test is positive a colonoscopy should be performed.

What are the symptoms for bowel cancer?

The most common symptoms are:

  • Changed stool (changed bowel habits - altered texture)
  • Blood in stool
  • Mucus secretion with the stool.
  • Stomach pain
  • Anaemia
  • Weight Loss

Bowel cancer is a "silent" disease that usually does not cause symptoms until it has progressed into an advanced stage and thus difficult to treat. 25% of people with bowel cancer have no symptoms until the disease has spread to other organs.

Who should be examined?

Basically, all over 50 years of age should be examined for bowel cancer. The optimal examination is colonoscopy. During the colonoscopy any polyps can be removed and examined. Read more about colonoscopy.

How is bowel cancer treated?

Today, the treatment of bowel cancer takes place in specialized hospital departments in close collaboration with oncological, pathological and medical-imaging departments. The main treatment principle is surgery where the tumor and the corresponding piece of the bowel are removed. In many cases it can be done by laparoscopic procedure. In more advanced cases, chemo- and radiotherapy may be necessary. Approx. 60% of patients with bowel cancer survives. Survival is entirely dependent on the stage the disease at the time it is detected. In the early stages, when the cancer has not spread or grown through the bowel, there is high chance (90%) for healing.