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:

  • Anoscopy or an exam of the anus and lower rectum using a short, lighted tube called an anoscope.
  • Proctoscopy, an exam of the rectum using a short, lighted tube called a proctoscope.

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.