There are five colon cancer stages (0-4). Colon cancer used to be rated using the Duke's system. For example, Duke's A cancer was the equivalent of stage 1 cancer. Sometimes you'll still hear people refer to their tumors that way, which can cause some confusion. The following breakdown should help clarify the basics of each colon cancer stage.
Stage 0 Colon Cancer
This is the earliest stage possible and is also called carcinoma in situ. "Carcinoma" refers to cancer that starts in epithelial tissue and "in situ" means original position or place. Colon cancer is considered stage 0 when it hasn't moved from where it started; it's still restricted to the innermost lining of the colon.
Stage 1 Colon Cancer
In this stage, cancer has extended beyond the innermost layer of the colon into the middle layers of the colon. Stage 1 used to be called Duke's A colon cancer.
Stage 2 Colon Cancer
This used to be called Duke's B colon cancer. Colon cancer is considered stage 2 after it moves beyond the middle layers of the colon. Sometimes colon cancer is still considered stage 2 after it has extended into nearby organs.
Stage 3 Colon Cancer
If colon cancer is found in at least three lymph nodes, it has reached stage 3 (formerly called Duke's C colon cancer).
Stage 4 Colon Cancer
Formerly referred to as Duke's D colon cancer, stage 4 is the most advanced colon cancer stage. In general, stage 4 colon cancer has spread to nearby lymph nodes and other parts of the body. Common destinations include the liver and the lungs.
Sources:
Assay. Merriam-Webster Online. Accessed 18 Jun. 2006 [http://m-w.com/cgi-bin/dictionary].
Carcinoma. Merriam-Webster Online. Accessed 18 Jun. 2006 [http://m-w.com/dictionary/carcinoma].
Colon Cancer (PDQ): Treatment: Stages of Colon Cancer. National Cancer Institute. Accessed 18 Jun. 2006 [http://www.cancer.gov/cancertopics/pdq/treatment/colon/Patient/page2].
In Situ. Merriam-Webster Online. Accessed 18 Jun. 2006 [http://m-w.com/dictionary/in%20situ].
