If you are diagnosed with colorectal cancer, your doctor will need to know how advanced
the disease is, or how far it has spread. The description of the extent of the disease
is known as staging. This section describes tests and definitions used in staging.
Colorectal cancer - tests involved in staging
The following are some of the procedures used in staging:
- Blood tests: The level of certain substances in the blood is checked.For
example, some people who have colorectal cancer or other conditions have a high
carcinoembryonic antigen (CEA) level.
- Biopsy: During a colonoscopy or sigmoidoscopy an abnormal growth
may be found in which doctors will want to take a sample, or biopsy. This sample
may come from the colon and/or rectal area. Other biopsies may also be taken of
nearby lymph nodes in order fully evaluate the stage of your disease and to determine
the best treatment for you.
- Colonoscopy: If a colonoscopy was not used for diagnosis, the entire
length of the colon and rectum is examined with a colonoscope to check for other
abnormal areas.
- Endorectal ultrasound (EUS): An ultrasound probe is inserted into
the rectum. The probe sends out sound waves (out of range of human hearing) that
bounce off the rectum and nearby tissues. A computer-generated picture, created
from the echoes, shows how deep a rectal tumor has grown or if the cancer has spread
to lymph nodes or other nearby tissues.
- Chest X ray: X rays of the chest can show whether cancer has spread
to the lungs.
- CT scan: An X-ray machine linked to a computer takes a series of
detailed pictures of areas inside the body. The patient may receive an injection
of dye. Tumors in the liver, lungs or other places in the body show up on the CT
scan.
The doctor also may use other tests, such as magnetic resonance imaging (MRI), to
see if the cancer has spread. Sometimes staging is not complete until the patient
has surgery to remove the tumor.
Colorectal cancer - stages of tumor growth
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Stage I
|
Cancer is confined and has not spread to neighboring tissue
|
|
Stage II
|
Cancer has spread beyond the original (primary) site, but there is no lymph node
involvement
|
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Stage III |
Cancer has spread beyond the original (primary) site to nearby lymph nodes but not
to other parts of the body
|
|
Stage IV |
Cancer has spread to distant organs
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Once your doctor has determined the stage of your cancer, you can then determine
the best approach to treating
your colorectal cancer.
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