The wall of the colon is made up of layers of tissue. Colon cancer occurs when abnormal cells form in the inner layer of this tissue. The cancer can grow through some or all of the other layers. The stage (extent) of the cancer depends to a great degree on how deep the cancer goes into these layers. Most colon cancers are called adenocarcinomas. Those are cancers that begin in cells that make and release mucus and other fluids.
Because the majority of colon cancers begin as precancerous polyps, colon cancer is a potentially preventable disease. Screening and early detection can catch colon cancer at an early stage or before polyps turn into cancer.1
Cancer of the colon is rare in developing countries, but is the second most frequent cancer in affluent societies. Worldwide, there are more than 940,000 cases (colorectal) and nearly 500,000 deaths each year.2 Colonoscopy is the most reliable means for early detection. Improved diagnosis and treatment have resulted in a five-year survival rate of 50 percent.2
- Read about Colon Cancer Symptoms.
- What You Need To Know About Cancer of the Colon and Rectum; National Cancer Institute. Available from: http://www.cancer.gov/cancertopics/wyntk/colon-and-rectal
- Global cancer rates could increase by 50% to 15 million by 2020; World Health Organization. Available from: http://www.who.int/mediacentre/news/releases/2003/pr27/en/