If you have signs of symptoms of colorectal cancer that last more than a couple weeks, you should see your doctor. He or she may perform tests to confirm a colorectal cancer diagnosis. Some of the symptoms of colorectal cancer are changes in bowel habits, rectal bleeding, blood in your stools, narrowing of stool, unexplained weight loss, and abdominal pain.
Colonoscopy
Depending on your age, personal and family history, and symptoms, your doctor may order a colonoscopy to look for colorectal cancer or other conditions that might be causing your symptoms. Colonoscopy is the most effective screening test for colorectal cancer, and it can also help prevent cancer from developing or spreading to other parts of the body because it offers the opportunity to find and remove polyps that may become cancerous.
During a colonoscopy, doctors use a tiny camera attached to a long, thin, flexible tube to get inside the colon to see the lining and look for polyps or abnormalities. During the procedure, the doctor can remove polyps and take samples of any suspicious looking intestinal tissue. This sampling of tissue is called a biopsy.
Depending on what the colonoscopy shows, your doctor will decide what next steps are. If he or she suspects colorectal cancer, tissue samples and polyps can be sent to a lab for testing. In some cases, your doctor may decide to perform an operation to remove tumors before the tissue has been tested. But in most cases, your treatment plan will be decided based on the results of the lab tests and other tests your doctor orders to help make a colorectal cancer diagnosis.
Diagnostic Tests for Colorectal Cancer
There are many tests used to diagnose and stage colorectal cancer. The most common test for diagnosis is colonoscopy, but there are others as well. Your doctor will decide which tests you should have based on a few factors, including:
- The type of cancer you are suspected of having
- The symptoms you are experiencing and signs you are exhibiting
- Your age, general health, and other medical conditions you may have
- Your personal medical history and family history
- The results of prior testing
When diagnosing colorectal cancer, your doctor will do a physical exam, take a personal and family medical history, and perform tests. Some tests are done to look for abnormalities, some are done to pinpoint what the abnormalities are, and some are done to find out whether cancer has spread and, if so, where it has spread. If your doctor suspects colorectal cancer, he or she will order one or more tests. In addition to colonoscopy, other tests may include:
- Biopsy – A biopsy involves removing a small portion of abnormal tissue so it can be examined to determine what type of cells the tissue consists of. This is the only test that can make a definitive diagnosis of colorectal cancer. A biopsy may be taken during a colonoscopy, or it can be done on tissue removed during surgery. Fine needle biopsies of intact tumor tissue may also be done with guidance from ultrasound or a CT scanner.
- Blood tests – A complete blood count (CBC) can test for anemia, which can be a sign of internal bleeding. Blood tests can also look for a protein called carcinoembryonic antigen, otherwise known as CEA. CEA may be an indicator that colorectal cancer has spread. This test is often used in people receiving treatment for colorectal cancer.
- Molecular testing of a tumor – Sometimes doctors test tumor tissue to identify certain genes or proteins that help identify the type of tumor. These tests can help pinpoint therapy. This is called targeted therapy.
- Computed tomography scan (CT scan; CAT scan) – CAT scans create 3D images of the inside of the body. They can be used to locate tumors and measure their size. CAT scans can be done with or without contrast dye. If used, the dye helps provide more detailed images. CAT scans can check for cancer throughout the body to determine whether colorectal cancer has spread to the lungs, liver, or other organs. This is often done to help stage cancer or to find out whether treatment is working.
- Magnetic resonance imaging scan (MRI scan) – MRI scans use magnetic fields to create images of the part of the body being tested. As with CAT scans, MRI scans provide more detailed images if a contrast solution is used. MRI scans are often used to find out where colorectal cancer has spread. Like CAT scans, MRIs are often done to help stage cancer or to find out whether treatment is working.
- Ultrasound – Ultrasound technology creates images of organs using sound waves. These pictures can help determine whether cancer has spread. Ultrasound can also view the depth of rectal cancer growth, which can help decide what the treatment plan should be. While ultrasound can help find tumors in the liver, CAT and MRI scans are better options for visualizing liver tumors.
- Chest x-ray – Chest x-rays help visualize the lungs to find out whether colorectal cancer has spread to the lungs.
- Positron emission tomography (PET) scan – A PET scan uses radioactive material to help “light up” cancer cells. A simple explanation of how PET scan works is that a radioactive sugar substance is injected into the veins, and as it travels to the organs, it is taken up by existing cancer cells. A CT scanner is used to see whether any areas of the body have taken up the radioactive substance. Because of the rate at which most cancer tissue grows, it is more likely to take up the substance, making this test helpful in seeing where cancer has spread. Most patients with colorectal cancer will not need PET scans, but doctors may recommend them in certain situations.
If you’re over 45, we recommend scheduling a screening colonoscopy – whether you have risk factors or not. If you do have risk factors, such as a family history or inherited colon cancer syndromes, you may need your screening colonoscopy earlier. Ask your doctor when the right time is for you to have yours.
Call (800) 633-7377 to ask for a referral for your colorectal cancer screen, and take control of your bowel health today.