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Diagnosis Cancer

Rectal Cancer

In making a diagnosis of rectal cancer, your doctor will first start by recording your medical history, asking about any symptoms you may be experiencing and conducting a thorough physical examination. He or she also may recommend one or more of the following diagnostic tests:

  • Digital Rectal Exam This exam involves the doctor or nurse inserting a gloved, lubricated finger into the rectum to feel for an abnormalities.
  • Barium Enema Also known as a lower gastrointestinal series, this test involves taking X-rays of the large intestines.
  • Fecal Occult Blood Test This is a noninvasive test that detects the presence of hidden, or occult blood in the stool. Such blood may arise from anywhere along the digestive tract. Hidden blood in the stool is often the first, and in many cases the only, warning sign that a person has colorectal cancer.
  • Sigmoidoscopy Sigmoidoscopy is performed to see inside the rectum and the lower colon and remove polyps or other abnormal tissue for examination under a microscope.
  • Colonoscopy Colonoscopy is performed to see inside the rectum and the entire colon and remove polyps or other abnormal tissue for examination under a microscope.
  • Polypectomy Polypectomy is performed during a sigmoidoscopy or colonoscopy to remove polyps.
  • Biopsy In a biopsy, a small amount of tissue from the suspected area is removed for examination by a pathologist to make a diagnosis.


If you are diagnosed with rectal cancer, your doctor needs to learn the stage or extent of your disease. Staging is a careful attempt to find out whether the cancer has spread and if so, to what parts of the body. This information also helps your doctor develop the best and most effective treatment plan for your condition. More tests — in particular an endorectal ultrasound (ERUS) or a magnetic resonance imaging (MRI) — may be performed to help determine the stage.

The various stages of rectal cancer include:

  • Stage 0 The cancer is very early. It is found only in the innermost lining of the rectum.
  • Stage I The cancer involves more of the inner wall of the rectum.
  • Stage II The cancer has spread outside the rectum to nearby tissue, but not to the lymph nodes. Lymph nodes are small, bean-shaped structures that are part of the body's immune system.
  • Stage III The cancer has spread to nearby lymph nodes, but not to other parts of the body.
  • Stage IV The cancer has spread to other parts of the body. If it spreads, rectal cancer tends to spread to the liver and lungs.
  • Recurrent: Recurrent cancer means the cancer has come back after treatment. The disease may recur in the rectum or in another part of the body.

UCSF Health medical specialists have reviewed this information. It is for educational purposes only and is not intended to replace the advice of your doctor or other health care provider. We encourage you to discuss any questions or concerns you may have with your provider.