Anal Cancer: Tests After Diagnosis

Ultrasound uses sound waves to look inside your body. The waves are sent out from a wand-like probe that's put into your rectum. The sound waves bounce off your insides and send back signals, like sonar on a submarine. A computer then receives the signals and makes an image of the inside of your body.

This test can help healthcare providers find out if the cancer has spread deep into the tissues around the anus or to nearby lymph nodes in your pelvis. It can also show how big the tumor is and how deep the cancer has grown into the wall of the anus.

For this test, you lie on a narrow table that moves through a ring-like CT scanner. It takes many X-rays as you slide through. A computer combines these images to make detailed pictures of your insides. You'll need to drink a special X-ray dye (contrast medium) just before the scan. Dye may also be put right into your blood through a vein in your arm or hand. The dye helps get clearer images.

This test can help show if the anal cancer has spread into your lymph nodes, liver, or other nearby organs. A CT scan is sometimes used to help guide the needle when doing a biopsy. A biopsy is when a tiny piece of tissue is taken out to check it for cancer cells.

MRIs use radio waves and magnets to make detailed pictures that look like slices of the body. You lie on a narrow table that slides through the long, narrow, tube-like scanner. Some people have trouble with this test because they don't like being in tight spaces. Let your healthcare provider know if this is a problem for you. You may be given medicine to help you do the test. A contrast dye will be put into a vein on your hand or arm before this test. This helps get better pictures.

MRIs can help your healthcare provider figure out where the tumor is and how big it is. They can also show if it’s spread to nearby tissues. For instance, MRI can show enlarged lymph nodes. This may be a sign that cancer has spread to them.

You may have an X-ray done to see if the cancer has spread to your lungs. Many times, a CT scan of the chest is used instead.

A PET scan shows tissues actively using sugar (glucose). Quickly dividing cells, like cancer cells, use up more of the glucose. For this test, a small amount of radioactive glucose is put in your blood through a vein in your arm or hand. Then you lie still on a table that moves through the ring-like PET scanner. It rotates around you, looking for the radioactivity. It takes a picture of your whole body that shows "hot spots" where a lot of radioactivity was found.

PET scans don't show a lot of detail, so they're often done along with a CT scan. This is called a PET/CT scan. The combination gives detailed pictures of where cancer may be anywhere in your body.