Tests and diagnosisBy Mayo Clinic staff
Tests and procedures used to diagnose anal cancer include:
- Examining your anal canal and rectum for abnormalities. During a digital rectal exam (DRE), your doctor inserts a gloved, lubricated finger into your rectum. He or she feels for anything unusual, such as growths. DRE isn't used to diagnose anal cancer, but it can give your doctor an indication of what further testing might be appropriate.
- 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 of your anal canal. In order 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 if the cells are cancerous.
Once it's confirmed that you have anal cancer, your doctor works to determine the size of the cancer and whether it has spread — a process called staging. Determining your cancer's stage helps your doctor determine the best approach to treating your cancer. Tests and procedures used in the staging of your cancer may include:
- Images of your pelvis and abdomen. Your doctor may use computerized tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET) to make scans of your pelvis and abdomen to assess the extent of your cancer.
- X-ray images of your chest. X-rays of your chest can reveal if cancer has spread to your lungs or the bones in your chest.
Your doctor uses the information from the procedures to assign your cancer a stage. The stages of anal cancer are:
- Stage I. Anal cancer is 2 centimeters (about 3/4 inch) or less — about the size of a peanut or smaller.
- Stage II. Anal cancer is larger than 2 centimeters (about 3/4 inch), but has not spread beyond the anal canal.
- Stage IIIA. Anal cancer is any size and has spread either to lymph nodes near the rectum or to nearby areas, such as the bladder, urethra or vagina.
- Stage IIIB. Anal cancer is any size and has spread to nearby areas and lymph nodes, or it has spread to other lymph nodes in the pelvis.
- Stage IV. Anal cancer has spread to parts of the body away from the pelvis.
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