Knowing the stage of colon and rectal cancers is an important step in trying to overcome the disease. Cancer stages are basically classifications for how far along the cancer has progressed, and if it has spread from its place of origin, how far. Typically, after your doctor diagnoses colorectal cancer, determining the stage is the next step. Once the stage is known, the best course of treatment can be recommended for your stage of cancer. Certain more aggressive treatments may not be necessary for stage 0 colorectal cancers, and if the cancer has reached stage IV, some treatment options may not be aggressive enough. This is why your prognosis goes hand-in-hand with what stage your cancer when it is diagnosed.
There are several tests doctors generally use to aid in determining the stage of colon and rectal cancers.
Eight of the most frequently used techniques are:
• Digital rectal examination
• Rigid proctoscopy
• Colonoscopy
• Computed tomography (CT) scan
• Magnetic resonance imaging (MRI) scan
• Endorectal ultrasound
• Positron emission tomography (PET) scan
• Carcinoembryonic antigen (CEA) blood testing
A digital rectal examination is used to determine if the tumor is capable of being felt within the rectal vault, and thus if it has spread to the anal sphincter. Some of the methods which utilize lighted tubes to examine to rectum and colon are rigid proctoscopies and colonoscopies. These tests can be used to measure the extent of a tumor’s growth or the presence of other cancerous polyps. CT scans use x-ray images which doctors use to look for additional tumors or growths which can indicate the spread of the disease.
MRI scans can be used for the same purpose and can also further examine the original tumor’s size and severity. Endorectal ultrasounds are used for similar purposes and also to check to see if local lymph nodes are affected. PET scans can locate cancer cells virtually anywhere in the body, as the test calls for the injection of radioactive sugar molecules into the body. Those molecules tend to migrate to and become concentrated where cancerous cells are present. CEA blood tests are used to locate substances given off by cancerous cells. These tests can be used to see how advanced colorectal cancer is, as well as in treatment to verify that treatment is working.