Colorectal cancer refers to a cancer that originates in the colon or rectum, affecting the large intestine and the digestive system. This type of cancer can also be known as colon cancer or rectal cancer. This depends on where the disease originally forms in the body.
Colorectal cancer is the fourth most common type of cancer in the United States. It typically starts as a growth, called a polyp, that can form on the inside lining of the colon or rectum. Some types of polyps become cancer in time, but not all become cancerous. The two main types of polyps include:
- Adenomatous polyps
- Hyperplastic polyps
Characteristics that can increase the chances that a polyp may be cancerous are:
- Size of polyp (larger than 1 cm)
- Number found in the body (more than two)
- Dysplasia in the polyp after it is removed
Dysplasia is a precancerous condition that may exist in a polyp or in the colon or rectum lining. Polyps can be removed from the body early in development in order to prevent the potential of colorectal cancer.
- The stage of colorectal cancer is determined by its level of penetration into the intestinal wall, regional lymph node involvement, whether there is evidence of distant spread to other organs.