Complete blood count: This test determines the number of different cell types in your blood. Reduced number of red blood cells is called anemia and may be seen in colorectal cancer patients with long term bleeding.
Liver enzymes: The levels of these enzymes may increase if the colorectal cancer spreads to the liver.
Tumor markers: Colorectal cancer cells sometimes cause formation of substances that are detectable in the blood. Most common tumor markers for colorectal cancers are carsinoembryonic antigen (CEA) and CA 19-9. Although these markers can be warning signs that suggest patient may have colorectal cancer, they are not used for diagnosis alone. These cancer markers may be found within normal ranges in the patients, and might increase due to non-cancer causes. They are more frequently used for treatment and follow-up purposes in patients who were diagnosed with colorectal cancer. These markers can be helpful for the evaluation of treatment success or early diagnosis of a relapsed cancer.
Your physician evaluates inner surface of entire colon and rectum by using a thin, soft tube with a light source and a small video camera at its tip. Biopsy samples can be taken with special tools inserted into the colonoscopy or suspected polyps can be removed if needed. Colonoscopy can be performed under clinic conditions.
If a lesion suspected for colorectal cancer is detected during a screening test, biopsy is performed there with the colonoscopy. A small tissue sample is taken by a special tool from the suspected region. More rarely, partial colon removal may be necessary for diagnosis purposes.
Imaging Tests for Colon and Rectum Cancer
Imaging tests can be used for different purposes;
Evaluation of the regions that may have cancer
Determination of the extent of cancer spread
Evaluation of treatment success
Computed Tomography (CT)
Detailed cross-sectional images of your body are obtained via CT and it is evaluated whether colon cancer has spread to the liver or other organs.
In this method, your organs are evaluated by using sound waves and images formed through the echos. When a device called probe with a small microphone at its tip is placed onto the abdominal region, data obtained by the echos of sound waves striking the organs are converted into images by a computer and displayed on a screen.
Endorectal ultrasonography: Performed by inserting a special probe into the rectum. It enables the evaluation of the depth of cancer on rectum wall, its relation with surrounding tissues and organs and the lymph nodes within that area.
Intraoperative ultrasonography: Procedure is performed during the operation. When the ultrasonography probe is directly put onto the liver, liver metastases can be evaluated in a more sensitive way.
Magnetic Resonance Imaging (MRI)
As with CT, MRI also provide cross-sectional images, however, radio waves and very powerful magnets are used instead of x-rays. MRI can be used to evaluate abnormal regions inside the liver, brain and spinal cord.
Endorectal MRI: This test provides a very detailed evaluation of rectum cancer, however, it requires at least 30-45 minutes of imaging by using a special probe placed inside the rectum.
Chest radiography: It is used to evaluate lung spread of the colorectal cancer, however, we prefer chest tomography for a more detailed examination.
Positron Emission Tomography (PET)
PET imaging requires an injection of radioactive sugar substance that represents involvement in cancer cells. Then, a special camera shows the involvement areas of this radioactive sugar. Images obtained here are not as detailed as CT or MRI, however, it may provide valuable information for determination of whether the areas appearing abnormal contain cancer. Test provides information about the spread of the disease in diagnosed patients.