Introduction
If intestinal cancer is suspected, the patient’s medical history (anamnesis) must first be taken. Of particular interest are signs of disease suspected of being tumorous as well as the family medical history with possible indications of an increased incidence of colorectal cancer. The patient should then undergo a thorough physical examination. The most important examination is a palpation of the rectum.
General information
Up to 60% of tumours can be palpated with a rectal palpation. In the case of higher-situated tumours, a tumour mass in the abdomen can sometimes be palpated. A haemoccult test is used to search for blood admixtures in the stool, which can occur due to tumour-related blood loss in the gastrointestinal tract.
From the age of 50, this test is also recommended for the prevention of colon cancer. Those who have a high incidence of family members suffering from intestinal cancer can also have a genetic test carried out to better assess their individual risk of developing cancer. When the blood is analysed (laboratory values), certain blood values can indicate a tumour disease.
For example, a low blood pigment content (haemoglobin) can indicate chronic blood loss, which is particularly common with this type of tumour. So-called tumour markers are substances in the blood that are found more frequently in some types of cancer and can therefore indicate cancer. Tumour markers are either formed by the tumours themselves or their formation is stimulated by them.
They do not play a significant role in the initial diagnosis of a colon carcinoma, as false-positive results are often found (positive tumour marker, but no cancer). If, however, a certain tumour marker value is found to be elevated before an operation, which disappears after the operation, this marker can be used particularly well to diagnose a renewed outbreak of the tumour (tumour recurrence) by means of a rapid blood test. The final confirmation of the diagnosis is made by a colonoscopy with tissue sampling. Images of a colonoscopy can be seen under the topic Colon Cancer.
Colonoscopy
Colonoscopy is the method of choice for direct assessment and classification of mucous membrane damage and should be performed if there is a suspicion of intestinal cancer. During this examination, images are transmitted to a monitor via a tube camera (endoscope). For this purpose, the camera is advanced to the end of the colon (caecum) and then, while slowly retracting, the mucous membrane is assessed.
During the colonoscopy, additional tissue samples (biopsy) can be taken from suspicious areas of the mucosa. Mirroring is also particularly suitable for removing larger mucous membrane growths (polyps) with a sling. Tissue assessment under the microscope (histological findings) is far more meaningful than the (macroscopic) findings recorded with the naked eye.
Only in the histological examination can the type of tumour be determined, as well as its spread in the layers of the intestinal wall. The so-called rectoscopy (recto-sigmoidoscopy) must be distinguished from this. This method allows the lower sections of the intestine (rectum, rectum and sigmoid) to be viewed through a rigid tube. As this examination can only see the end of the intestine, it offers no advantages over colonoscopy and is therefore not routinely used in tumour diagnostics.
