Anal cancer is often fairly easy to diagnose because it is in a fairly easy-to-reach area. Some cases of anal cancer in people at high risk for that disease are diagnosed by screening tests, such as the digital rectal exam and/or anal Pap test, but most people are diagnosed after their cancer starts to cause symptoms.
 

Signs and symptoms of anal cancer

Some cases of anal cancer cause no symptoms at all. In more than half of patients, bleeding occurs and is often the first sign of the disease. The bleeding is usually minor. At first, most people assume that hemorrhoids are the cause of their bleeding. Itching can also be a symptom. This is more often a sign of AIN, which should also be treated. Important symptoms of anal cancer include:

• rectal bleeding
• rectal itching
• pain in the anal area
• change in the diameter of stool
• abnormal discharge from the anus
• swollen lymph nodes in the anal or groin areas

There are a number of benign conditions, such as hemorrhoids, fissures, fistulas, and anal warts that can cause similar symptoms. But if any of the signs or symptoms of anal cancer are present, discuss them with your doctor without delay. Remember, the sooner you receive a correct diagnosis, the sooner you can start treatment, and the more effective your treatment will be.
 

Procedures used to diagnose anal cancer

Sometimes a doctor will detect anal cancer during a routine physical exam or during a minor procedure, such as removing a hemorrhoid. Treating cancers found in this way is often very effective because the tumors are found early in the course of the disease.
 

An unusual growth may also be found on a digital rectal exam. But since doctors cannot see what they feel, other steps may be needed if you have symptoms or if your doctor suspects you have anal cancer.
 

Endoscopy

Endoscopy is the use of a tube with a lens or video camera on the end to examine an inner part of the body. Several types of endoscopy may be used to look for the cause of anal symptoms. For these tests you either lie on your side on top of an examining table, with your knees bent up to your chest, or you bend forward over the table. Types of endoscopy include:
 

Anoscopy: Anoscopy uses a short, hollow tube (an anoscope), which is 3 to 4 inches long and about 1 inch in diameter, and may have a light on the end of it. The doctor coats the anoscope with a lubricant and then gently pushes it into the anus and rectum. By shining a light into this tube, the doctor has a clear view of the lining of the lower rectum and anus. This is usually not painful.
 

Rigid proctosigmoidoscopy: The rigid proctosigmoidoscope is similar to an anoscope, except that the proctoscope is 10 inches long, so it allows the doctor to view the rectum as well as the lower part of the sigmoid colon. This test usually requires that you take laxatives or have an enema beforehand to make sure the bowels are empty.
 

Biopsy

If a suspicious growth is found, your doctor will need to take a sample of tissue to see if it is cancer. This is called a biopsy. This can often be done through the scope itself. You may get a local anesthetic to numb the area before the biopsy is taken. Then, a small piece of the tissue is cut out and sent to a lab.
 

A pathologist (a doctor specializing in lab diagnosis of diseases) will look at the sample under a microscope. If cancer is present, the pathologist will send back a report describing the cell type and extent of the cancer.
 

If the tumor is very small and has not grown below the surface of the anus into other tissues, your doctor may attempt to remove the entire tumor during the biopsy.
 

Fine-needle aspiration biopsy: Anal cancer sometimes spreads through the lymphatic system to lymph nodes. Lymph nodes are bean-sized collections of immune system cells. Swollen lymph nodes in the groin can be a sign of spreading anal cancer. Lymph nodes may also become swollen from an infection. To see 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. The lab will study this fluid to look for the presence of cancer cells. This procedure is called a fine-needle aspiration biopsy. If cancer is found in a lymph node, an operation to remove the lymph nodes in that area may then be done.
 

Sentinel node biopsy: This test is sometimes used to help determine if cancer that has already been diagnosed has spread to the lymph nodes. In this test a low-level radioactive tracer material is injected around the tumor. Often a blue dye is injected into the tumor at the same time. The groin lymph nodes are scanned to see where the radioactive material has traveled. The doctor removes any radioactive or blue-stained lymph nodes. A pathologist then looks at the nodes for evidence of cancer cells. This helps tell how far the cancer may have spread, because these nodes would be the ones that any cancer cells leaving the tumor would have spread to first. While this test has been shown to be useful for some other cancers, it's not yet clear how helpful it is for anal cancer.