What Is Colorectal Cancer?

Colorectal cancer includes two types of cancers: cancer of the colon (large intestine or bowel) referred to as colon cancer, and cancer of the rectum (the end portion of the large intestine) or rectal cancer. Both types of cancer have many features in common, so they are collectively called colorectal cancer.  The colon and the rectum form part of the digestive tract, also called the gastrointestinal or GI tract.

The Colon’s Main Functions Are To:

RE-Absorb-Icon

Re-absorb water and some nutrients such as the salts sodium, potassium and chloride from what we eat

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Formation and compaction of waste

Fermentation of some indigestible food matter by beneficial bacteria

The rectum’s main function is to temporarily store waste before it is excreted through the anus.

Generally, colorectal cancer spreads fairly slowly, more slowly than some other cancers. It can stay in the colon or rectum for months or years, and, if it is not treated, can spread to other parts of the body. If caught in the early stages, colorectal cancer is often curable.

Most colorectal cancers evolve from small mushroom-like growths known as polyps. Sometimes the polyps can be flat, making them harder to detect. While most polyps are benign (non-cancerous), as they evolve they may become cancerous. 

Over time, the benign polyp may grow through some or all of the tissue layers that make up the colon and rectum and become malignant, invading nearby tissues and structures. Eventually, malignant tumour cells can reach the blood and lymphatic system and travel to other parts of the body such as the liver or lungs, causing cancer to develop in these organs. The spread of the cancer to another organ is called metastasis.

Keeping up to date with colorectal cancer screening is an important part of prevention. A screening test checks for the presence of colorectal cancer when there are no signs and symptoms of the disease. Participating in screening helps to remove precancerous polyps before they become cancerous and helps to detect colorectal cancer at an earlier stage, when the cancer is more treatable.

Early-stage disease can present very minor colorectal cancer symptoms, sometimes presenting no symptoms at all.  This underlines the importance of keeping up to date with screening.

Common signs and symptoms of colorectal cancer

  • Rectal bleeding
  • Blood in or on the stool, ranging from bright red to dark black

  • Unexplained changes in bowel habits, like constipation or diarrhea

  • Change in size/shape of stools, such as being narrower than usual

  • The urge to have a bowel movement but nothing passes, also called tenesmus

  • Consistent abdominal pain or discomfort, including bloating, fullness, cramping and gas pain
  • Anemia due to iron deficiency
common-signs-and-symptoms-of-colon-cancer

Many of these signs may also be caused by other gastrointestinal conditions, such as Crohn’s disease, ulcers or hemorrhoids, but they should always be discussed with your doctor to receive the correct diagnosis. If you are experiencing any signs or symptoms of colorectal cancer, be sure to talk to your doctor without delay.

Colorectal cancer risk factors

  • Age – your risk increases as you get older
  • Inflammatory bowel disease such as Crohn’s disease or ulcerative colitis
  • A personal or family history of colorectal cancer or colorectal polyps

  • An inherited syndrome such as Lynch syndrome or familial adenomatous polyposis (FAP)

Colorectal cancer risk factors

Risk Factors
  • Age – your risk increases as you get older
  • Inflammatory bowel disease such as Crohn’s disease or ulcerative colitis
  • A personal or family history of colorectal cancer or colorectal polyps
  • An inherited syndrome such as Lynch syndrome or familial adenomatous polyposis (FAP)

Certain lifestyle factors may also contribute to an increased risk of developing colorectal cancer:

  • Lack of physical activity
  • A diet low in fruits and vegetables
  • A low-fibre and high-fat diet, or a diet that is high in processed meats
  • Overweight and obesity
  • Excessive alcohol consumption
  • Excessive tobacco use