Further tests for anal cancer

If your tests show that you have anal cancer, you may need further tests to see if the cancer has spread. Further tests will help your doctor to decide which treatment is most suitable for you.

Anal cancer most commonly spreads to the lymph nodes in your tummy (abdomen) and the groin. Fluid from body tissues drains into lymph vessels and passes through the lymph nodes before draining into the bloodstream. If any cancer cells have broken away, they can travel to the lymph nodes in tissue fluid.

You have this test under a general anaesthetic. The anaesthetic allows your muscles to relax so your specialist is able to examine the suspicious area more easily and can see how far the cancer has spread. The specialist may take a sample of tissue (a biopsy), if you haven't already had one taken.

This is a type of X-ray that takes pictures from different angles. The pictures are fed into a computer to form a detailed picture of the inside of your body. Your doctor uses the scan to check whether the cancer has spread anywhere else in your body. Before a CT scan you may be asked

• Not to eat or drink for four hours before the test
• To drink a special liquid a few hours before the test
• To drink more of the liquid in the X-ray department

Just before the scan, the doctor may put more liquid into your rectum. 

The liquid (contrast medium) is a dye that shows up body tissues more clearly on the scan. Before you have this, the doctor or nurse will check if you have any allergies or asthma as some people can be allergic to the contrast.

There is more about having a CT scan in the section about cancer tests.

This scan uses magnetism to build up a picture of the inside of the body. It can show up soft tissues very clearly, and can give more detail than a CT scan. So MRI scans are often used for anal cancers.

There is more general information about MRI scans in the section about cancer tests.

Ultrasound scans use sound waves to build up a picture of the inside of the body. This can help the doctor to find out how far the cancer has grown into nearby tissue. To have a rectal ultrasound, the doctor puts a small ultrasound tube into your back passage (rectum). This is uncomfortable, but should not hurt. Your rectum needs to be empty beforehand, so you will need to make sure you’ve had a bowel movement before having this test.

Your doctor might want you to have a PET-CT scan. A PET-CT scan combines a CT scan and a PET scan into one scan. A PET scan uses a very small amount of an injected radioactive drug to show structures in the body.

A PET-CT scan takes CT pictures of the structures of your body. At the same time, the mildly radioactive drug shows up areas of your body where the cells are more active than normal. The scanner combines both of these types of information. This allows your doctor to see any changes in the activity of cells and know exactly where the changes are happening. For people with anal cancer, it can help to see if the cancer has spread to the nearby lymph nodes, or help doctors to stage the cancer if it comes back.

PET-CT scanners are quite new, and only some hospitals in the UK have them at the moment. So you may have to travel to another hospital if you need to have one. There is more information about PET-CT scans in our cancer tests section.

You will be asked to come back to the hospital when your test results have come through. This is bound to take a little time, even if only a week or so. You are likely to feel anxious during this time.

While you are waiting for results it may help to talk to a close friend or relative about how you are feeling. You may also have a specialist nurse you can talk to during this time. Or you may want to contact a cancer support group to talk to someone who has been through a similar experience. Ask your nurse at the hospital, or look at our general organisations section for ways of finding support groups or counselling services near you.