Before deciding on treatment options, your doctor will need to know the extent, or stage, of the anal cancer. Your doctor may schedule one or more of the following tests to help determine the stage of anal cancer:
Transrectal ultrasound. This test can help doctors find out if the cancer has spread around the anal area or to lymph glands in your pelvis. Ultrasound uses sound waves to look for problems. The waves are emitted from a probe inserted into the rectum. The sound waves bounce off body parts and send back signals, like sonar on a submarine. A computer then receives the signals and creates an image of the inside of the body. This test is very helpful in detecting masses inside the body and learning more about them.
Pelvic computed tomography scan (CT scan). This test can help tell if your anal cancer has spread into your liver or other organs. A CT scanner takes many X-rays as you slide through it on a table. A computer combines these images to create detailed pictures that your doctor can view.
Pelvic magnetic resonance imaging (MRI). MRIs can show more detail than other X-rays and can help a doctor figure out the location, size, and stage of the cancer. MRIs use radio waves and magnets. The energy from the radio waves creates patterns formed by different types of tissue and diseases. This produces cross-sectional pictures that look like slices of the body.
Chest X-ray or chest computed tomography scan (CT scan). You may have one of these tests to see whether the anal cancer has spread to your lungs.
Positron emission tomography scan (PET scan). The PET scan reveals tissues actively using glucose. Glucose use is a sign of increased metabolic activity as seen in quickly dividing cells, such as anal cancer cells. For this test, you get injected with a small amount of radioactive glucose. Then, you lie still on a table that is pushed into the PET scanner, which rotates around you, detecting the radioactivity. This is converted into a picture of your whole body, showing "hot spots" where a lot of radioactivity was detected.