Doctors describe colorectal cancer by the following stages:
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Stage 0: The cancer is found only in the innermost lining of the colon or rectum. Carcinoma in situ is another name for Stage 0 colorectal cancer.
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Stage I: The tumor has grown into the inner wall of the colon or rectum. The tumor has not grown through the wall.
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Stage II: The tumor extends more deeply into or through the wall of the colon or rectum. It may have invaded nearby tissue, but cancer cells have not spread to the lymph nodes.
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Stage III: The cancer has spread to nearby lymph nodes, but not to other parts of the body.
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Stage IV: The cancer has spread to other parts of the body, such as the liver or lungs.
http://www.cancer.gov/cancertopics/wyntk/colon-and-rectal/page8
