Colorectal Cancer Diagnostic Tests

The following tests may be used to for colon cancer screening or to find out if the cancer has spread. Tests also may be used to find out if surrounding tissues or organs have been damaged by treatment.

  • Digital rectal exam (DRE): The doctor inserts a gloved finger into your rectum to feel for polyps or other problems.
  • Fecal occult blood test (FOBT): This take-home test finds blood in stool.
  • Fecal immunochemical test (FIT): This take-home test finds blood proteins in stool.
Doctor talking with nurses

Endoscopic Tests, which may include:

  • Sigmoidoscopy: A tiny camera on flexible plastic tubing (sigmoidoscope) is inserted into the rectum. This gives the doctor a view of the rectum and lower colon. Tissue or polyps can be biopsied (removed) and looked at under a microscope.
  • Colonoscopy: A longer version of a sigmoidoscope, a colonoscope can look at the entire colon.
  • Endoscopic ultrasound (EUS): An endoscope is inserted into the rectum. A probe at the end 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 axial tomography) scan
  • MRI (magnetic resonance imaging) scan
  • PET/CT (positron emission tomography) scan
  • Virtual colonoscopy or CT (computed tomography) colonoscopy
  • Double contrast barium enema (DCBE): Barium is a chemical that allows the bowel lining to show up on an X-ray. A barium solution is given by enema, and then a series of X-rays are taken.

Blood test for carcinoembryonic antigen (CEA):  CEA is a protein, or tumor marker, made by some cancerous tumors. This test also can be used to find out if the tumor is growing or has come back after treatment.


Surgery is the most common treatment for colorectal cancer, especially if it has not spread. Our surgeons are among the most experienced in the country and have helped establish national quality standards for the treatment of colorectal cancer. They have also developed novel methods to improve staging accuracy and have published the first randomized trial ever evaluating staging methods in colon cancer.

Colorectal cancer may be treated with surgery alone, surgery and chemotherapy, and/or other treatments.

The Type of Surgery Depends on the Stage and Location of the Tumor:

  • Polypectomy: A colonoscope, which is a long tube with a camera on the end, is inserted into the rectum and guided to the polyp. A tiny, scissor-like tool or wire loop removes the polyp.
  • Colectomy: The area of the colon where the cancer is, along with some healthy surrounding tissue, is removed. The associated lymph nodes are removed (biopsied) and looked at under a microscope. Usually the surgeon then rejoins the parts of the colon. This surgery also is called a hemicolectomy or partial colectomy.

Your doctor will decide whether it is best to perform traditional open surgery or minimally invasive laparoscopic surgery. Saint Johns’ surgeons are very experienced in minimally invasive surgery to treat colorectal cancer.

Minimally-invasive, or Laparoscopic Surgery

During minimally invasive surgery, small cuts are made in the abdomen. A tiny camera and surgical instruments are inserted through the cuts and the surgeon uses video imaging to perform the surgery. More recently the surgeons have been certified in the use of the robot to further improve the accuracy of the surgery.

Endoscopic Mucosal Resection (EMR) may be used if the cancer is small and only on the surface of the colon. A needle is placed in the colon wall, and then saline (saltwater) is injected to make a bubble under the growth. Using suction, the lesion is removed.

Endoluminal stent placement. This minimally invasive procedure uses an endoscope to place expanding metal stents to help relieve a bowel obstruction.

Chemotherapy or Radiation May Be Given:

  • When used before surgery to make the cancer smaller, it’s called neoadjuvant therapy.
  • When used post-surgery, it’s called adjuvant therapy.


Treating your colorectal cancer may involve the most up-to-date and effective chemotherapy available. Drugs are given either orally or intravenously.

Chemotherapy may be used to help:

  • Shrink the cancer before surgery
  • Keep you cancer free after surgery
  • Prolong life when surgery is not an option

Targeted Therapies

Providence Saint John’s offers targeted therapies for certain types of colorectal cancer. Using innovative new drugs we work to stop the growth of cancer cells by interfering with certain proteins and receptors or blood vessels that supply the tumor with what it needs to grow, survive and spread.

Radiation Therapy

Our advanced radiation treatments include:

  • Brachytherapy: Tiny radioactive seeds are placed in the body close to the tumor.
  • 3D-conformal radiation therapy: Several radiation beams are given in the exact shape of the tumor.
  • Intensity-modulated radiotherapy (IMRT): Treatment is tailored to the specific shape of the tumor to reduce damage to normal tissue.