Bowel cancer

How does cancer develop?

Cancer usually develops when healthy cells change. Healthy cells grow and divide in a very orderly way to maintain the functions of our body. Sometimes, however, this growth gets out of control. As a result, cells divide when they are not needed. They can also take on a number of properties that healthy cells do not have. These include the ability to penetrate into neighbouring tissue or to continue to grow far from the actual place of origin and thus form what are known as metastases.

From polyps to bowel cancer
In most cases, bowel cancer develops from initially benign cell accumulations, called polyps, which result from the uncontrolled growth of cells in the colon and rectum. These can develop into bowel cancer over the course of years. In later stages of the disease, the cancer can then penetrate the entire wall, grow into neighbouring organs and cause lymph node and distant metastases. Polyps can develop anywhere in the colon and rectum: the colon measures about 1.5 metres in length, the rectum 16 centimetres. Polyps are either mushroom-shaped or completely flat. They can be just a few millimetres in size, but can also reach a few centimetres in diameter. Even such large polyps can be completely asymptomatic.

Other risk factors

Other factors, such as obesity, lack of exercise, diabetes and smoking, as well as high alcohol consumption, can also encourage the development of bowel cancer.

Age

About 90 per cent of patients with bowel cancer are over 50 years of age. Although bowel cancer can also occur at a younger age, this is rare.

Medical history

People who have already suffered from bowel cancer or who have had polyps have a higher risk of developing bowel cancer in the future and should therefore undergo regular checks.

Inflammatory bowel diseases

Long-standing chronic inflammatory bowel disease (ulcerative colitis) represents an increased risk of bowel cancer.

Genetic factors

There are genetic diseases that can increase the risk of bowel cancer in a family. These account for about 5 per cent of all diseases. 

Dietary habits

A low-fibre diet and a high proportion of animal fats and calories have long been associated with increased development of bowel cancer. This also includes the consumption of red meat. 

Causes and risk factors of bowel cancer

As with most other cancers, the exact cause of bowel cancer is still unknown. However, there are a number of diseases or risk factors related to bowel cancer that are associated with an increased incidence.

Tumour markers

Tumour markers are protein compounds that are formed by certain malignant tumours and can be detected in the blood. Bowel cancer is particularly characterised by the tumour marker CEA (carcinoembryonic antigen). However, these tumour markers are not very specific because they also occur in healthy individuals and are not produced by every tumour. They are therefore only suitable for monitoring the progress of cancer treatment.

Endosonography

During an endosonography, a transducer is inserted into the rectum. The examination provides information about the depth of penetration of a tumour as well as about enlarged lymph nodes and the relationship between a tumour and the sphincter.

Ultrasound (sonography)

Many changes, especially in the liver, can be visualised very well with the help of ultrasound. The completely harmless examination, in addition to other imaging procedures, allows the stages to be classified precisely.

Magnetic resonance imaging (MRI)

The MRI provides high-resolution images to accurately assess the rectum and pelvic organs. Especially in the case of rectal cancer, valuable information about the depth of the penetration of a tumour, its relationship to the neighbouring organs, lymph node metastases and other changes can be obtained as part of treatment planning. MRI is also crucial for assessing the liver.

Virtual colonoscopy (CT colonoscopy)

What is known as a virtual colonoscopy is based on high-resolution computed tomography and offers a high degree of accuracy. However, the procedure is associated with radiation exposure. A conventional colonoscopy is necessary if unclear changes are detected in the intestinal mucosa.

Colonoscopy

During a colonoscopy, the entire colon and rectum are examined with a flexible instrument. Each section of the intestinal wall can be checked precisely. If necessary, polyps can be removed straight away and then examined under the microscope. This enables us to make an exact statement about their condition. If you wish, you can be given a mild sedative shortly before the examination so that you do not feel any pain. A preventive colonoscopy is covered by health insurance from the age of 55. It is generally carried out on an outpatient basis by a doctor in their own practice or, in the event of risks, as an inpatient in a hospital. Please ask your GP.