Diagnosis

Doctors use many tests to diagnose cancer and determine if it has metastasized (spread). Some tests may also determine which treatments may be the most effective. For most types of cancer, a biopsy is the only way to make a definitive diagnosis of cancer. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis. Imaging tests may be used to find out whether the cancer has metastasized. Your doctor may consider these factors when choosing a diagnostic test:

• Age and medical condition
  
  
• The type of cancer suspected
  
  
• Severity of symptoms
  
  
• Previous test results

In addition to a physical examination, the following tests may be used to diagnose anal cancer:

Digital rectal examination (DRE). During this test, the doctor inserts a gloved finger into the anus to feel for lumps or abnormalities. General cancer guidelines suggest men have a DRE annually after the age of 50 and women have one during routine pelvic examinations. If you are at higher risk for developing anal cancer, your doctor may perform a DRE more often.

Anoscopy. If the doctor feels a suspicious area during a DRE, this endoscopic test may be performed to see the abnormality. An anoscopy allows the doctor to see inside the body with a thin, lighted, flexible tube called an anoscope. Similarly, a proctoscope can be used to view the rectum (a procedure called a proctoscopy). The person may be sedated as the tube is inserted into the anus and/or rectum.

Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis. The sample removed during the biopsy is analyzed by a pathologist (a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease). The type of biopsy performed will depend on the location of the cancer. For instance, an excisional biopsy can remove the entire lump if it is small and does not extend into other tissues. Lymph nodes may also be examined in a biopsy.

Ultrasound. An ultrasound uses sound waves to create a picture of the internal organs. In an anal ultrasound, an ultrasound wand is inserted into the anus to obtain the pictures.

Computed tomography (CT or CAT) scan. A CT scan creates a three-dimensional picture of the inside of the body with an x-ray machine. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. Sometimes, a contrast medium (a special dye) is injected into a patient’s vein to provide better detail.

Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. A contrast medium may be injected into a patient’s vein to create a clearer picture.

Positron emission tomography (PET) scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive substance is injected into a patient’s body and absorbed by the organs or tissues being studied. This substance gives off energy that is detected by a scanner, which produces the images.

X-ray. An x-ray is a picture of the inside of the body. For instance, a chest x-ray can help determine if the cancer has spread to the lungs.

Learn more about what to expect when having common tests, procedures, and scans.

Find out more about common terms used during a diagnosis of cancer.