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The diagnosis of bowel cancer is made by means of imaging exams, such as colonoscopy and rectosigmoidoscopy, and by examining stool, especially the examination of occult blood in the stool. These tests are usually indicated by the doctor when the person has signs and symptoms of bowel cancer, such as the presence of blood in the stool, changes in the intestinal rhythm and weight loss. Here's how to recognize the symptoms of bowel cancer.
Usually, these tests are requested for people over 50, who have a family history of illness or who have a risk factor, such as obesity, diabetes and a low fiber diet, for example. However, these tests can also be recommended even if there are no symptoms, just as a form of screening, since diagnosis in the early stages of the disease increases the chance of cure.
As there are several tests that investigate the presence of this type of cancer, the doctor should request the most suitable for each person, taking into account factors such as health status, the risk of cancer and the cost of the test. The main tests performed are:
1. Search for occult blood in stool
The fecal occult blood test is the most widely used in bowel cancer screening, as it is practical, inexpensive and non-invasive, requiring only the collection of a stool sample by the person, which must be sent to the laboratory for analysis. .
This test aims to identify the presence of blood in the stool that is not visible, which can happen in the early stages of bowel cancer and, therefore, it is indicated that people over 50 years old have the test annually.
If the occult blood test is positive, the doctor must indicate that other tests are carried out to confirm the diagnosis, and colonoscopy is mainly indicated, because in addition to cancer, bleeding can also be caused by polyps, hemorrhoids, diverticulosis or fissure. anal, for example.
Currently, this test is done with a new technique, called an immunochemical test, which is more advantageous than the traditional method, since it detects smaller amounts of blood and does not suffer from interference from foods, such as beets.
Learn more about fecal occult blood research.
2. Colonoscopy
Colonoscopy is a very effective diagnostic test to identify intestinal changes, as it is able to visualize the entire large intestine and, if changes are observed, it is still possible during the exam to remove suspicious lesions or remove a sample for biopsy. On the other hand, colonoscopy is a procedure that requires intestinal preparation and sedation to be done.
Therefore, colonoscopy is indicated for people who have altered results in the occult blood test, are over 50 years old or have signs or symptoms that are suggestive of bowel cancer, such as constipation or unjustified diarrhea, presence of blood and mucus in the stool. Learn more about the colonoscopy exam.
3. Virtual colonoscopy by computed tomography
Virtual colonoscopy is an exam that creates three-dimensional images of the intestine using computed tomography, being able to observe both the external wall of the intestine and its interior.
It is a great test, as it can detect lesions such as cancer or polyps without the need for sedation, as in colonoscopy. However, despite its advantages, virtual colonoscopy is expensive, requires preparation of the intestine and whenever changes are detected, it may be necessary to complement the investigation with colonoscopy.
4. Opaque enema
Opaque enema is an imaging test that also helps identify changes in the intestine that may arise during cancer. To be done, it is necessary to insert a contrast liquid through the anus and then do an X-ray which, due to the contrast, is able to form images of the colon and rectum.
Currently, this test is not widely used to detect bowel cancer, because in addition to the complexity to be done, it can cause some discomfort or pain. In addition, it does not allow the removal of samples for biopsy in the laboratory, and is often replaced by tomography and colonoscopy.
Understand how this exam works and how to prepare.
5. Retosigmoidoscopy
To perform this examination, a rigid or flexible tube is used with a small video camera at the tip, which is introduced through the anus and is able to observe the rectum and the final part of the large intestine, allowing the detection and removal of suspicious lesions. This test is more suitable for people over 50 years old, every 3 or 5 years, together with the search for occult blood in the stool.
Although it is also an exam capable of identifying bowel cancer, it is not usually requested by the doctor, since colonoscopy provides more information.
6. Fecal DNA test
Fecal DNA testing is a new test to screen for bowel cancer, also targeted at people over 50 or according to medical advice, as it is able to identify changes in the DNA of cells that indicate cancer or precancerous lesions, such as polyps.
Its advantages include not needing any preparation or changes in the diet, just collect a stool sample and send it to the laboratory. However, whenever suspicious changes are identified, confirmation with another test, such as colonoscopy, is required.