Colorectal Cancer

Colorectal cancer, also known as bowel cancer, colon cancer, or rectal cancer, is any cancer that affects the colon and the rectum.

Colorectal cancer is a cancer that starts in the colon or the rectum. Most colorectal cancers start as a growth on the inner lining of the colon or rectum. The colon and rectum make up the large intestine (or large bowel), which is part of the digestive system, also called the gastrointestinal (GI) system.

Adenocarcinomas make up about 96 per cent of colorectal cancers. These cancers start in cells that make mucus to lubricate the inside of the colon and rectum. When doctors talk about colorectal cancer, they're almost always talking about this type.

  • Adenocarcinomas: start in cells that make mucus to lubricate the inside of the colon and rectum.
  • Carcinoid tumours: start from special hormone-making cells in the intestine.
  • Gastrointestinal stromal tumours (GISTs): start from special cells in the wall of the colon called the interstitial cells of Cajal. Some are not cancerous (benign). These tumours can be found anywhere in the digestive tract, but are not common in the colon.
  • Lymphomas: mostly start in lymph nodes, but they can also start in the colon, rectum, or other organs.
  • Sarcomas: start in blood vessels, muscle layers, or other connective tissues in the wall of the colon and rectum. Sarcomas of the colon or rectum are rare.

Screening can detect polyps before they become cancerous, as well as detecting colon cancer during its early stages when the chances of a cure are much higher.

The following are the most common screening and diagnostic procedures for colorectal cancer:

  • A special test to see if there blood in your stool may be one of the first tests.
  • Flexible sigmoidoscopy: uses a flexible, slender and lighted tube, to examine the patient's rectum and sigmoid. The sigmoid colon is the last part of the colon, before the rectum. The test takes a few minutes and is not painful, but it might be uncomfortable. If the doctor detects polyps or colon cancer, a colonoscopy can then be used to examine the entire colon and take out any polyps that are present. These will be examined under a microscope.
  • Barium enema X-ray: : Barium is a contrast dye that is placed into the patient's bowel in an enema form, and it shows up on an X-ray. In a double-contrast barium enema, air is added as well. If the barium enema X-ray detects anything abnormal, the doctor may recommend a colonoscopy.
  • Colonoscopy: A colonoscope is longer than a sigmoidoscope. It is a long, flexible, slender tube, attached to a video camera and monitor. The doctor can see the whole of the colon and rectum. Any polyps discovered during this exam can be removed during the procedure, and sometimes tissue samples or biopsies are taken instead. A colonoscopy is painless, but some patients are given a mild sedative to calm them down. Before the exam, they will be given instructions about a special laxative fluid to take before the procedure clean out the colon.
  • Imaging scans: Imaging, like a CT or MRI, can provide specialists with a visual output where, if something is detected, further testing may be required.

If you’ve been diagnosed with colorectal cancer, your cancer care team will discuss your treatment options with you and help you to weigh the benefits of each treatment option against the possible risks and side effects.

Treatments might include surgery, chemotherapy (also called systemic therapy) and/ or radiation.

Based on your treatment options, you might have different types of specialists on your treatment team. These doctors could include:

  • Gastroenterologist: a doctor who treats disorders of the gastrointestinal (GI or digestive) tract
  • Surgical oncologist (oncologic surgeon): a doctor who uses surgery to treat cancer
  • Colorectal surgeon: a doctor who uses surgery to treat diseases of the colon and rectum
  • Radiation oncologist: a doctor who treats cancer with radiation therapy
  • Medical oncologist: a doctor who treats cancer with medicines such as chemotherapy or targeted therapy

Related Topics