Colorectal Cancer
Learn more about colorectal cancer and how it’s treated.
Overview
Colorectal cancer is any cancer that affects the colon and rectum. It is also known as bowel cancer, colon cancer, or rectal cancer. The colon and rectum make up the large intestine, which is part of the digestive system. Most colorectal cancers start as a growth on the inner lining of the colon or rectum.
Types of colorectal cancer
Adenocarcinomas
Adenocarcinomas are cancer that start in the glands that line your organs. They can show up in different parts of your body. In colorectal cancer, they start in the cells that produce the mucus that lubricates the inside of the colon and rectum.
Adenocarcinomas are the most common type of colorectal cancer, making up about 95 per cent of cases. When physicians talk about colorectal cancer, they are almost always talking about this type.
Carcinoid tumours
Carcinoid tumours affect hormone-producing cells and can occur throughout the body, though they often start in the gastrointestinal system. Most grow very slowly.
Gastrointestinal stromal tumours (GISTs)
Gastrointestinal stromal tumours (GISTs) start from special nerve cells in the wall of the colon and other digestive organs. These cells signal your muscles to help move food through the digestive system. A tumour can form when these cells grow and divide too much.
Not all GISTs are cancerous. These tumours can be found anywhere in the digestive tract, but they are not common in the colon.
Lymphomas
Lymphomas are a type of cancer that starts in the lymphatic system. Because lymphoid tissue exists throughout the body, lymphoma can start in many places. Lymphomas that start in the colon are very rare.
Sarcomas
Sarcoma is a type of cancer that starts in blood vessels, muscle layers, or other connective tissue. Sarcomas of the colon or rectum are rare but can occur.
Colorectal cancer screening
Many people with colorectal cancer have no symptoms until the cancer is more advanced and more difficult to treat. Regular screening — even if you do not have any symptoms — can help detect colorectal cancer earlier, when it is much more likely to be cured.
Diagnosis
Physicians use several tests used to diagnose colorectal cancer, and more than one is often needed for an accurate diagnosis.
Learn about colorectal screening and diagnosis.
Fecal immunochemical test (FIT)
A fecal immunochemical test (FIT) checks a small stool sample for blood, including blood that may not be visible to the eye.
A FIT is usually one of the first tests used to check for colorectal cancer.
Flexible sigmoidoscopy
Flexible sigmoidoscopy allows a physician to see your rectum and sigmoid, the last part of the colon before the rectum.
During the test, a flexible, slender tube with a light and camera is inserted through the anus. The test takes a few minutes. It is not painful, but it may be uncomfortable.
If the physician finds polyps (clumps of cells that can become cancerous over time) or colon cancer, they may recommend a colonoscopy to examine the entire colon and remove any polyps for further examination.
Barium enema X-ray
A barium enema X-ray helps the physician look at your lower intestine. Before the X-ray, the technician injects a liquid containing a substance called barium sulfate through the rectum (an enema) to make the image clearer. In a double contrast barium enema, the technician also adds air through the rectum as well.
If anything abnormal shows up on your barium enema X-ray, the physician may recommend a colonoscopy.
Colonoscopy
A colonoscopy is a procedure that lets physicians examine the large intestine (colon and rectum). During a colonoscopy, a long, flexible, slender tube attached to a video camera is inserted through the anus. This lets the physician see the entire colon and rectum on a monitor.
During this exam, physicians remove any polyps (clumps of cells that can become cancerous over time) they find and take tissue samples (biopsies) when needed.
Diagnostic imaging
Imaging — such as computed tomography (CT) scans or magnetic resonance imaging (MRI) — helps physicians clearly see your colon and rectum. If something is detected, you may need further testing.
Cancer staging
If cancer is found, the next step is determining its stage. Knowing the stage of your cancer helps your care team develop your treatment plan. Physician determine the stage based on the size and location of the tumour, whether cancer cells are in the lymph nodes, and whether there are cancer cells in other parts of the body.
Treatment
If you are diagnosed with colorectal cancer, your Cancer care team will discuss your treatment options and help you weigh the benefits of each against the possible risks and side effects.
Surgery is the most common treatment for colorectal cancer. During this surgery, your surgeon removes the tumour, along with part of the healthy colon and nearby lymph nodes.
In some cases you may need a combination of chemotherapy, radiation and surgery to treat colorectal cancer.
Clinical trials
You may be able to join a research study that helps physicians and researchers find ways to improve treatments and quality of life for patients living with colorectal cancer.