The severity of a cancer is defined by progressive stages. For instance, colon cancer Stage I has not spread as far as colon cancer Stage 2. The colon cancer staging system is used universally and was developed by the American Joint Committee on Cancer (AJCC) and the International Union Against Cancer. The stages of colon cancer are as follows:
- Cancer is limited to the colon’s innermost lining and has not spread beyond that. This earliest stage is also referred to as carcinoma in situ.
- Cancer has spread to the colon lining’s middle layers, but not to lymph nodes, other tissue or organs. This stage is also referred to as Dukes’ A colon cancer.
Also referred to as Dukes’ B colon cancer, this stage is broken down into three sub-stages.
- Stage IIA – Cancer has grown, but is still contained within the colon or rectum’s outermost layers. It has neither penetrated the layers nor spread to lymph nodes, other tissue or organs.
- Stage IIB – Cancer growth has penetrated the colon or rectum’s wall, but has not spread to lymph nodes, other tissue or organs.
- Stage IIC – The cancer has metastasized (spread) to tissue or organs near the colon, but has not affected lymph nodes or distant tissue and organs.
This stage is also called Dukes’ C colon cancer. The three sub-stages of this stage are:
- Stage IIIA – Cancer has not yet spread to distant sites, but is found in the colon wall’s middle layers and one to three lymph nodes.
- Stage IIIB – Cancer has not yet spread to distant sites. One of three possibilities exist: cancer has spread to one to three lymph nodes and has grown through or into the colon or rectum’s outer layers; cancer has spread to four to six lymph nodes and has grown into the outer or middle colon or rectum layers; or cancer has spread to seven or more lymph nodes and has grown into the middle or first layers of the colon or rectum.
- Stage IIIC – Cancer has spread through the exterior layers of the colon or rectum and to four to six neighboring lymph nodes; cancer has spread into or through the exterior layers of the colon or rectum and to at least seven neighboring lymph nodes; or cancer has spread into or through the exterior layers of the colon or rectum, to at least one neighboring lymph node and has also spread to neighboring organs.
This stage is also called Dukes’ D colon cancer and includes two sub-stages. In Stage IV, cancer has possibly spread through the colon wall or rectal wall and may have spread to neighboring lymph nodes.
- Stage IVA – Cancer has has metastasized to one distant organ such as the liver or lungs and one distant set of lymph nodes; or it as spread to more than one distant organ or distant parts of the abdominal cavity (peritoneum).