Colorectal Cancer - Exams and Tests
If your doctor thinks you may have colorectal cancer, he or she will ask you questions about your medical history and give you a physical exam. Other tests may include:
- A colonoscopy, a test in which your doctor uses a lighted scope to view the inside of your entire colon. A colonoscopy may be done to look into symptoms such as unexplained bleeding from the rectum, constant diarrhea or constipation, blood in the stool, or pain in the lower abdomen. A colonoscopy is recommended when another screening test shows you may have colorectal cancer.2
- A sigmoidoscopy, a test in which your doctor uses a lighted scope to view the lower part of your intestine. A sigmoidoscopy may be done to look into symptoms such as unexplained bleeding from the rectum, constant diarrhea or constipation, blood in the stool, or pain in the lower abdomen. Doctors can also remove polyps during this test.
- A barium enema, in which a whitish liquid with barium is inserted through your rectum into your intestine. The barium outlines the inside of the colon so that it can be seen on an X-ray.
- A biopsy, in which a sample of tissue is taken from the inside of your intestine and examined under a microscope. A doctor called a pathologist can look at the tissue sample and see if it contains cancer.
- A complete blood count, which is a blood test. It is used to look into symptoms such as fatigue, weakness, anemia, bruising, or weight loss.
For people who have an increased risk for colorectal cancer, regular colonoscopy is the recommended screening test because it allows your doctor to remove polyps (polypectomy) and take tissue samples at the same time.
When you are diagnosed with colorectal cancer, your doctor may order other tests to find out whether the cancer has spread. These tests include:
- A CT scan to see if the cancer has spread to your liver, lungs, or abdomen.
- A chest X-ray to see if the cancer has spread to your lungs.
- An MRI or PET scan to see if the cancer has spread into your chest or organs in the abdomen or pelvis.
- An ultrasound to find the cause of abdominal pain or increased abdominal girth or to see if the cancer has spread to your liver. An endoscopic ultrasound is used to see how far rectal cancer may have spread.
- A blood chemistry panel to see if the cancer has spread to your liver and bones.
- A carcinoembryonic antigen (CEA) blood test to check the level of this tumor marker.
Early Detection
Colorectal cancer has a much better chance of being successfully treated when it is found early. Most people who get colorectal cancer are older than 50 and have no other risk factors besides their age. See the What Increases Your Risk section of this topic for more information.
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