If tests show that you have colorectal cancer, additional examinations may be performed to determine its extent -- a process called staging. Knowing how far your cancer has progressed is important when deciding what regimen of treatment might be most appropriate for you. The following tests are routinely used to stage colorectal cancer:
- computed tomography (CT and magnetic resonance imaging (MRI) scans, which may be used to see if the cancer has spread to other organs, such as the liver and lungs
- chest x-ray, which may be performed to see if the cancer has spread to the lungs
- blood tests for CEA, a protein that acts as a marker for colorectal cancer
Depending on your specific clinical situation, these additional tests may be ordered:
- positron-emission tomography (PET) scanning, which may be conducted to find other places where cancer may be lurking
- angiography, which may be done to find blood vessels next to cancer that has spread to the liver, allowing doctors to plan surgery to minimize blood loss
- endorectal ultrasound probe, which uses sound waves to produce an image of the tumor; it may be placed in the rectum to see how far a cancer has invaded the rectal wall. This procedure is used for staging rectal cancer only.
