Diagnosis

Tests and procedures used to diagnose anal cancer include:

• Examining your anal canal and rectum for abnormalities. During a digital rectal exam, your doctor inserts a gloved, lubricated finger into your rectum. He or she feels for anything unusual, such as growths.
• Visually inspecting your anal canal and rectum. Your doctor may use a short, lighted tube (anoscope) to inspect your anal canal and rectum for anything unusual.
• Taking sound wave pictures (ultrasound) of your anal canal. To create a picture of your anal canal, your doctor inserts a probe, similar to a thick thermometer, into your anal canal and rectum. The probe emits high-energy sound waves, called ultrasound waves, which bounce off tissues and organs in your body to create a picture. Your doctor evaluates the picture to look for anything abnormal.
• Removing a sample of tissue for laboratory testing. If your doctor discovers any unusual areas, he or she may take small samples of affected tissue (biopsy) and send the samples to a laboratory for analysis. By looking at the cells under a microscope, doctors can determine whether the cells are cancerous.

Determining the extent of the cancer

Once it's confirmed that you have anal cancer, your doctor may recommend additional tests to determine whether your cancer has spread to your lymph nodes or to other areas of your body.

Tests may include:

• Computerized tomography (CT)
• Magnetic resonance imaging (MRI)
• Positron emission tomography (PET)

Your doctor uses the information from the procedures to assign your cancer a stage. The stages of anal cancer are indicated using Roman numerals ranging from 0 to IV, with the lowest stages indicating that the cancer is small and confined to the anus. By stage IV, the cancer has spread to distant areas of the body.

The cancer staging system continues to evolve and is becoming more complex as doctors improve cancer diagnosis and treatment. Your doctor uses your cancer stage to select the treatments that are right for you.