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Rectal Cancer Diagnosis

Finding rectal cancer early greatly increases your chance for effective treatment. If diagnosed early, many rectal cancers can be treated successfully.

At MD Anderson, our specialists have remarkable expertise and skill in diagnosing rectal cancers. And they use the most advanced equipment and techniques to help them customize the best treatment for you. We are one of the leading centers in advanced rectal MRI evaluation and virtual colonoscopy (also called CT or computed tomography colonoscopy).

Rectal Cancer Diagnosis

If you have symptoms that may signal rectal cancer, your doctor will examine you and ask you questions about your health; your lifestyle, including smoking and drinking habits; and your family medical history.

One or more of the following tests may be used to find out if you have rectal cancer and if it has spread. These tests also may be used to find out if treatment is working.

Digital rectal exam: The doctor inserts a gloved finger into the rectum to feel for polyps or other problems.

Fecal occult blood test (FOBT): This take-home test looks for blood in stool. A stool sample is examined for traces of blood not visible to the naked eye.

Fecal immunochemical test (FIT): This take-home test detects blood proteins in stool.

Endoscopic tests, which may include:

Proctoscopy: A thin, tube-like instrument (proctoscope) is inserted into the rectum. This lets the doctor view the rectum. Suspicious tissue or polyps can be biopsied (removed) for examination.

Sigmoidoscopy: Flexible plastic tubing with a camera on the end (sigmoidoscope) is inserted into the rectum. This gives the doctor a view of the rectum and lower colon. Suspicious tissue or polyps can be biopsied (removed) for examination. The tumor can be marked to help the doctor do minimally invasive surgery. Also called flexible sigmoidoscopy or flex-sig.

Colonoscopy: A colonoscope is a longer version of a sigmoidoscope. Doctors use it to look at the entire colon.

Endoscopic ultrasound (EUS): An endoscope is inserted into the body. A probe at the end of the endoscope bounces high-energy sound waves (ultrasound) off internal organs to make a picture (sonogram). Also called endosonography.

Imaging tests, which may include:

  • CT or CAT (computed tomography) scan
  • MRI (magnetic resonance imaging) scan
  • PET/CT (positron emission tomography) scan
  • Virtual colonoscopy or CT (computed tomography) colonoscopy: A scope is not put into the rectum, and you do not have to be sedated.
  • Double contrast barium enema (DCBE): Barium is a chemical that allows the bowel lining to show up on X-ray. A barium solution is given by enema. Then a series of X-rays are taken.

Blood test for carcinoembryonic antigen (CEA): This blood test looks for CEA, a tumor marker made by most rectal cancers. It also can be used to measure tumor growth or find out if cancer has come back after treatment.

Rectal Cancer Staging

If you are diagnosed with rectal cancer, your doctor will find the stage of the disease. Staging is a way of determining how much disease is in the body and where it has spread. This information helps the doctor plan the best way to treat the cancer. Once the staging classification is determined, it stays the same even if treatment works or the cancer spreads.

Patient Tip

Don't dwell on statistics. This is your experience, and no two people, cancer diagnoses or experiences are exactly alike.

Rectal Cancer Stages

(source: National Cancer Institute)

Stage 0: Abnormal cells are found in the innermost lining of the rectum. These abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 also is called carcinoma in situ.

Stage I: Cancer has formed and spread into the first (submucosa) or second (muscle) layers of the rectal wall. It has not spread outside of the rectum.

Stage II: Cancer has spread outside of the rectal walls into the surrounding fat or nearby tissue. It has not gone into the lymph nodes. It is divided into stages IIA, IIB, or IIC depending on the extent of local tumor involvement.

Stage III: Cancer has spread to nearby lymph nodes. It has not spread to other parts of the body. It is divided into stages IIIA, IIIB, or IIIC depending on the extent of local tumor involvement and the number of lymph nodes that contain cancer.

Stage IV: Cancer has spread to other parts of the body, such as the liver, lungs or ovaries. It is divided into stages IVA and IVB depending on the number of different other parts of the body to which the cancer has spread.

Clinical Trials

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Knowledge Center

Find the latest news and information about rectal cancer in our Knowledge Center, including blog posts, articles, videos, news releases and more.