Health Care Zone

Anal Cancer Diagnostic Test and Procedure Explained

Anal Cancer Diagnostic Test or Procedures: Anal cancer can be diagnosed during routine medical exams or during minor procedures such as the removal of hemorrhoids. It may also be diagnosed by a digital rectal examination (DRE), when a doctor inserts a gloved, lubricated finger into the anus to feel for unusual growths.

For prompt and early detection of anal cancer, the American Cancer Society recommends that all people above 50 years old should have a DRE every five to 10 years. [Note: Being above 50 is considered a risk factor of the disease.]

Other anal cancer diagnostic test or procedure include:

If your doctor finds a suspicious growth during anoscopy or protoscopy, he will do a biopsy. This is the removal of cells or tissues from your anus, which a pathologist will view under a microscope to check for signs of cancer.

Swollen lymph nodes can be a sign of spreading anal cancer—but they may also become swollen from an infection. To check if cancer is causing an enlarged lymph node, your doctor may withdraw a small sample of fluid and tissue from the lymph node with a thin needle. This fluid will be studied for the presence of cancer cells. This is called the fine-needle aspiration biopsy.

In cancer that has already been diagnosed, sentinel node biopsy may be used to help determine if the cancer has spread to the lymph nodes. In this test, a low-level radioactive tracer material is injected around the tumor and blue dye is injected into the tumor at the same time.

The groin lymph nodes are then scanned to see where the radioactive material has traveled, as these nodes would be the ones that any cancer cells leaving the tumor would have spread to first. However, while this test has been useful in many cancers, it’s not yet clear how helpful it is for anal cancer.

If your doctor has already diagnosed anal cancer, he may order various imaging studies to determine its spread. These include chest-x-rays, ultrasounds, computed tomography or CT scans, magnetic resonance imaging or MRI scans and positron emission tomography or PET scans.

Ultrasound uses sound waves and their echoes to take a picture of your internal organs and masses. A small microphone-like instrument, or transducer, emits high-frequency sound waves that pass into the body parts being studied, from which they are echoed back.

The transducer picks up these echoes, which a computer then converts these into an image on the screen. Ultrasounds are very safe and use no radiation.

For most ultrasound exams, the transducer is placed on the skin, but for anal cancer, the transducer is inserted directly into the rectum to see how deep the cancer has grown into the anal tissues. This is known as transrectal or endorectal ultrasound, and it can be slightly uncomfortable but is usually not painful.

Computed tomography or CT scan may be used to tell if the anal cancer has spread into the liver or other organs. This is an x-ray procedure that produces detailed cross-sectional images of your body parts.

Unlike a standard x-ray, a CT scanner will not take one picture but will take many pictures as it rotates around you. A computer then combines these “sliced images” into a complete image of the part of your body being studied.

Before a scan, you may be asked to drink 1 to 2 pints of a liquid called “oral contrast” to help “coat” the intestine so that certain areas are not mistaken for tumors.

You may also receive an IV (intravenous) line through which a different kind of contrast dye (IV contrast) is injected to help produce a better outline of your body structures.

This injection can cause some “flushing” or redness and a warm feeling that may last hours to days. A few people may even be allergic to the dye and will get hives. More serious allergic reactions, like trouble breathing and low blood pressure, do happen, but rarely.

Be sure to tell the doctor if you have ever had a reaction to any contrast material used for x-rays. Medicine can be given to prevent and treat allergic reactions. Because CT scans take longer than regular x-rays and you need to lie still on a table while these are being done, you might feel a bit confined.

Magnetic resonance imaging or MRI scans use radio waves and strong magnets instead of x-rays to make images. Radio waves is absorbed by the body and then released in a specific pattern, which a computer translates into a detailed image of body parts being examined.

Like a CT scanner, MRI scanners produces cross-sectional slices of the body. A contrast material might be used, but it is not needed as often.

Because you have to be placed inside tube-like equipment, MRI scans are more uncomfortable than CT scans and take longer to complete—often up to an hour. They are confining and can upset people who suffer from claustrophobia.

If you have trouble with closed spaces, medication can be given just before the scan to reduce anxiety or a special “open” MRI machine that is less confining can be used.

The MRI machine also makes a buzzing or clanging noise that some people may find disturbing. Some hospitals and clinics will provide headphones with music to block this sound.

When your doctor thinks the cancer has spread, but doesn’t know where, a positron emission tomography or PET scan can be done to determine the spread accurately, since this type of machine scans your entire body. Instead of taking several different x-rays, a single PET scan can be done.

PET scans use glucose that contains a low-level radioactive atom to identify cancer cells. Because they are very active, cancer cells absorb larger amounts of the sugar than normal cells and display more radioactivity. A special camera can be used to detect this radioactivity.


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