Symptoms
The dangerous thing about colorectal cancer is that it does not produce characteristic early symptoms. This means that the disease can remain undetected for a long time. The same applies to potential precancerous stages, such as polyps.
These are usually a chance finding during a colonoscopy. Polyps can seldom make themselves noticeable by slimy, possibly bloody stools. Constipation or diarrhea can also be signs of a polyp.
Colorectal carcinoma (another term for colorectal cancer) is usually also asymptomatic. However, when blood is added to the stool, colorectal cancer should be considered, especially at an advanced age. Unfortunately, these bleedings are not always visible.
In such cases, they are occult (hidden) bleedings which can only be detected by diagnostic tests (haemocult). Since about half of all colorectal cancer patients also have hemorrhoids, blood in the stool should not always be attributed to hemorrhoids. Although they are often the cause of bleeding, they are also frequently associated with colorectal cancer.
Therefore, a bleeding should also be clarified by a physician. Changes in stool habits can also be a sign of intestinal cancer. Constipation and diarrhoea can occur alternately (= paradoxical diarrhoea) or individually.
So-called pencil stools, which are very thin stools, are also observed. Colon cancer can also manifest itself in unintentional defecation in flatus. However, these symptoms are not always present and therefore good screening for early detection is very important.
In addition to the specific symptoms, cancers in general, including colorectal cancer, can also cause a so-called B-symptom. These are non-specific accompanying symptoms caused by an existing malignant disease. These include unwanted weight loss, fever, night sweats.
Other symptoms can include reduced performance and general fatigue. Abdominal pain is a very unspecific symptom. There are many conceivable causes that can lead to abdominal pain.
Typically, abdominal pain is not a symptom of colon cancer.In other words: Colon cancer is a rare cause of abdominal pain. However, abdominal pain can be caused by diseases that increase the risk of developing colorectal cancer or can result from colorectal cancer. In general, abdominal pain is not initially a reason to think of a malignant disease.
Here too, attention should be paid to the accompanying symptoms and the type and intensity of the pain. An ileus (intestinal obstruction), for example, can be the cause of very severe abdominal pain. This can be caused by the relocation of the intestine as a result of a tumor disease.
However, an ileus can also have many other causes. In addition to the severe pain, there is usually nausea as well as gushing vomiting. The course of the disease is very acute.
In the context of other gastrointestinal diseases, which are accompanied by abdominal pain, the risk of developing colorectal cancer may be increased. These include chronic inflammatory bowel diseases such as ulcerative colitis or Crohn’s disease. Depending on the course of these illnesses, in addition to abdominal pain, there are chronic complaints of the digestive tract, which can manifest themselves for example in diarrhea or deficiency symptoms of certain nutrients.
Especially at an advanced age, bleeding in the stool should be clarified by a doctor as soon as possible. Until the contrary is proven, there is a suspicion of colorectal carcinoma. This cautious attitude is absolutely necessary in order not to overlook a malignant disease.
Of course, blood in the stool can also have another source such as hemorrhoidal bleeding. The blood in the stool in hemorrhoids is light red in color. In the case of colorectal carcinoma, the bleeding can look quite different.
Typical for a rectal bleeding is light-colored blood in the stool. In a bleeding from the colon, the blood is rather dark and jelly-like. Both bleedings belong to the lower gastrointestinal bleedings because they affect the lower digestive tract.
However, a melena is also conceivable. This is the so-called tarry stool, which is black. Although such a bleeding is typical for the upper digestive tract, it can also occur in colorectal cancer.
The color is caused by degradation and metabolic processes. Blood in the stool, however, as already mentioned, can also be caused by bleeding in the ear, nose and throat and other parts of the digestive tract and is not a proving criterion for colorectal cancer. It is very difficult to differentiate the bleedings as a layman.
Therefore further diagnostic clarification by a physician is very important. Also, blood in the stool is not always visible. There is a screening method for the detection of hidden (occult) bleeding in the stool.
It is called haemoccult test or guaiac test. The test requires a total of three stool samples from three consecutive bowel movements. The blood is detected by means of filter paper and hydrogen peroxide.
If the test result is positive (blood is present) the test strip turns blue. However, the test has certain weak points. Positive results may be obtained erroneously because other stool components, such as myoglobin, may also color the test strip blue.
Myoglobin is a muscle protein that can accumulate in the stool from the consumption of red meat. It also detects blood that does not come from the intestines. Gum or nose bleeding and hemorrhoidal bleeding are often responsible for false positive results.
