The longest part of the large intestine is the colon. When cancer forms in these tissues, it is known as colon cancer. The National Cancer Institute estimates that in 2009, there will be nearly 106,100 new diagnoses of colon cancer in the United States.
Staging
Cancers are staged, usually from Stage 0 or Stage I, to Stage IV, in order of severity. The staging of a cancer helps guide treatment, prognosis, and describes how far the cancer has spread, according to the National Cancer Institute. Some stages of various cancers, including colon cancer, have substages.
Stage IIIA
In this Stage IIIA of colon cancer, the cancer has spread through the inner layer of colon wall tissue to the middle layer, and has spread to up to three lymph nodes, according to the National Cancer Institute.
Stage IIIB
In Stage IIIB, the cancer has not only spread to up to three lymph nodes, but it has also spread either past the middle layers of the wall of the colon, tissues around the rectum or colon, or past the colon wall into adjoining organs and/or the peritoneum, which is the lining of the abdominal wall.
Stage IIIC
To be diagnosed as Stage IIIC, the cancer has spread to at least four lymph nodes and to or past the middle layer of the wall of the colon, to tissues around the rectum or colon, or to adjoining organs or through the lining of the abdominal wall.
Identification
Stage III colon cancer is also called Dukes C colon cancer. Colon and rectal cancer are also sometimes called colorectal cancers, regardless of which organ is affected, according to the National Cancer Institute.
Prognosis
Cancer survival is often discussed in terms of five-year survival rates, which means the percentage of people surviving at least five years past the time they are diagnosed. The American Cancer Society lists the survival rate of Stage III colon cancer as: for Stage IIIA, it is 83 percent; Stage IIIB, 64 percent; and Stage IIIC, 44 percent.
