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How does colorectal cancer start?

Most cancers develop on the inner lining of the large bowel from gland-type polyps. Polyps are flat lesions, like a pitcher's mound on a baseball diamond, or as pedunculated lesions like a mushroom. Some polyps are harmless and others grow to become cancerous. The pathway from normal mucosa, through a polyp stage to a cancer can take about ten years. Some cancers are more aggressive.

Colon Cancer Facts
What is colorectal cancer?

Colon cancer is 90% curable if caught early -- if caught late, it is 90% fatal. Colon cancer is the second leading cause of cancer death in North America. In 2017 the Canadian Cancer Society estimates that 26,800 Canadians were diagnosed with colorectal cancer and 9,400 of us died from it. Put another way, 1 in 13 men and 1 in 16 women will be diagnosed with colorectal cancer. That's the bad news. Thankfully, with screening this cancer can be prevented or diagnosed early on when it is still curable.

What are the signs of colorectal cancer?

Often, there are none. Colon cancer may lie hidden in the body until it is large. By then, it is often too advanced to cure. Common signs and symptoms include:

  • blood in your stool

  • a change in your bowel habits

  • abdominal discomfort, cramps, gas pains

  • a feeling of not being able to empty all of your stool during a bowel movement

  • weight loss and fatigue

  • a mass that can be felt on abdominal or rectal examination

What are the risk factors?
  • age over 50 (age over 45 if African-American)

  • a family history of colon cancer

  • a personal history of polyps

  • inherited disorders that predispose to cancer (FAP and HNPCC)

  • inflammatory bowel disease like Crohn's disease or ulcerative colitis

  • red meat and processed meat consumption

  • alcohol

  • obesity

  • sedentary lifestyle

  • diabetes
  • smoking

  • prior abdominal radiation therapy