Your doctor will ask about your symptoms, and medical and family history. The abdominal and rectal areas will be carefully examined. Your doctor may recommend different tests in order to identify abnormal growths and confirm diagnosis.
Bowel changes can be caused by many different factors. The following tests can be done in the office to start to look for signs of cancer or other possible problems. Tests may include:
Imaging and/or visual tests may be used to look for tumors. The tests can also show the size and location of tumors. Some tests use contrast material to highlight structures so images are more clear and detailed. Imaging tests may include:
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A virtual colonoscopy is a type of CT scan that takes detailed images of the rectum and colon. It does not require the insertion of a tube into the colon. Some of the benefits of a virtual colonoscopy include:
However, if there is any suspicious-looking tissue, a colonoscopy will have to be done to remove it.
Colorectal cancer may be suspected based on tests above. A biopsy will confirm cancer is present. A biopsy is a tissue sample that is removed from the colon or rectum. After removal, the sample is examined under a microscope. This is the only way to confirm a diagnosis.
Results from completed tests and new tests will help determine the stage of cancer. Staging is used to determine the prognosis and treatment plan. Factors that play a role in staging include how far the original tumor has spread, whether lymph nodes are involved, if cancer has spread to other tissue, and microscopic cellular or genetic details.
Tests that may help determine colorectal cancer stage:
The colon and rectal walls are made of up 4 layers, the innermost mucosa, the submucosa, a thicker muscle layer, and a thin serosa. The location and depth of the tumor is important in staging. Colorectal cancer is staged from 0-IV.
Benson AP, Venook AB, Cederquist L, et al. Colon Cancer. Version 2.2017. In: National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines in Oncology (NCCN Guidelines). NCCN 2017 Mar from NCCN website.
Colon cancer treatment option overview. National Cancer Institute website. Available at: https://www.cancer.gov/types/colorectal/patient/colon-treatment-pdq#section/_135. Updated January 30, 2020. Accessed February 27, 2020.
Colorectal cancer. American Cancer Society website. Available at: http://www.cancer.org/acs/groups/cid/documents/webcontent/003096-pdf.pdf. Accessed February 27, 2020.
Colorectal cancer. EBSCO DynaMed website. Available at:https://www.dynamed.com/condition/colorectal-cancer. Updated January 22, 2020. Accessed February 27, 2020.
Glynne-Jones R, Wyrwicz L, Tiret E, et al. Rectal cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Ann Oncol. 2017 Jul 1;28.
Stages of rectal cancer. National Cancer Institute website. Available at: https://www.cancer.gov/types/colorectal/patient/rectal-treatment-pdq#section/_111. Updated January 30, 2020. Accessed February 27, 2020.
Last reviewed December 2019 by Mohei Abouzied, MD Last Updated: 2/27/2020