How Is Colon Cancer Diagnosed?

There are several screening tests that can potentially detect colon cancer in its earliest stages, when more treatment options are generally available. This is significant because early diagnosis and treatment can greatly enhance a patient’s outcome and quality of life. For average-risk individuals, the American Cancer Society currently recommends regular colorectal cancer screenings beginning at age 50.

Colon cancer screening is effective and saves many lives. However, it is also important to be vigilant for potential warning signs of the condition, such as a change in bowel habits, rectal bleeding and abdominal pain. While many of these symptoms can be caused by other, less serious conditions, such as infections, hemorrhoids and irritable bowel syndrome, it is still important to bring them to the attention of a physician right away so that the cause can be diagnosed and treated.

Diagnostic tests for colon cancer

If colon cancer is suspected based on a patient’s symptoms, a physician will generally begin the diagnostic process with a physical examination. This may include a visual and manual assessment of the abdomen as well as a digital rectal exam, during which the physician will insert a gloved finger into the rectum to check for palpable polyps. The physician may also order one or more of the following tests:

  • Fecal occult blood test – A stool sample is tested in a lab for the presence of blood.
  • Fecal immunohistochemistry test – A stool sample is tested in a lab for the presence of certain proteins produced by cancerous cells.
  • Sigmoidoscopy – A physician checks for visible polyps in the lower colon (a common precursor to colon cancer) using a slim tube and small camera inserted through the rectum.
  • Colonoscopy – A physician checks for visible polyps in the entire colon (this test is similar to a sigmoidoscopy, but more comprehensive).
  • Rectal endoscopic ultrasound – A physician inserts a small ultrasound device into the rectum to capture high-quality images.

If you are experiencing symptoms of colon cancer, you are welcome to consult with an oncologist in the Gastrointestinal Oncology Program at Moffitt Cancer Center. Contact Moffitt by calling 1-888-663-3488 or completing our new patient registration form online. You do not need a referral.