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Healthcare provider speaks with patient about diagnosis of colon cancer.

If a physician suspects that a patient has colon cancer, the diagnosis can be confirmed – or ruled out – through several specialized tests. To start the diagnostic process, a physician will typically perform a medical history and physical exam. Both of these tests are usually done in the same visit. A medical history is simply a verbal discussion of a patient’s symptoms and previous health conditions; a physical exam allows the physician to check for any immediately detectable signs of cancer. The physical exam usually involves a manual assessment of a patient’s abdomen as well as a digital rectal exam, during which a physician inserts a gloved finger into the patient’s rectum to check for the presence of palpable polyps.

What tests are used to diagnose colon cancer?

If the results of a patient’s medical history and physical exam suggest that colon cancer is a possible diagnosis, more advanced tests can then be performed. These include:

Fecal occult blood test

This is a take-home test that checks for the presence of blood in a patient’s stool (one of the primary colon cancer symptoms).

Fecal immunohistochemistry test

This test is performed to assess a stool sample for the presence of certain proteins that are produced by cancerous cells.


During this procedure, a slim tube with a small camera at the end is inserted into a patient’s rectum and lower colon so that a physician can visually check for unusual growths.


A colonoscopy is a slighting more extensive version of a sigmoidoscopy, during which a physician visually assesses the entire colon (rather than only the bottom portion).

Endoscopic ultrasound

During this procedure, an endoscope is inserted into a patient’s rectum, where it bounces sound waves off the internal organs to produce an image known as a sonogram.


A biopsy involves removing a small sample of tissue to be examined under a microscope. The biopsy might be performed during a colonoscopy or using tissue that was removing during a surgery.

Molecular testing

Following a biopsy, certain lab tests can be run on the tumor tissue sample to identify certain genes, proteins and other tumor properties. Molecular testing is useful in determining a patient’s most appropriate treatment options.

Imaging tests

Various methods of imaging – including CT scans, MRIs, X-rays or PET scans – may be used to create images of organs and tissues in the body to identify tumors and assess cancer growth/spread.


Anyone who is experiencing the symptoms of colon cancer can discuss a potential diagnosis with the expert oncologists at Moffitt Cancer Center. We offer a complete range of diagnostic tests and treatment services in a single location, and no referrals are required. To learn more about the tests we offer to investigate a potential colon cancer diagnosis, call 1-888-663-3488 or submit a new patient registration form online.

Helpful Links:

Reports Show Rise in Colorectal Cancer Among Young Adults