The stage of colorectal cancer describes whether the cancer has remained within the bowel or has spread to other sites. As with all cancers, the appropriate therapy can be decided only when the stage of the cancer has been defined.
There have been a number of staging systems for colorectal cancer. The original system developed by Dr. Dukes in 1932 has been modified several times. Since 1985, a staging system based on the Tumor/ Nodes/Metastases (TNM) classification that corresponds directly with the Dukes system has been used. This allows an improved definition for the number of lymph nodes involved, a factor that can affect the prognosis . The 1990 National Cancer Institute Consensus Panel recommended using the TNM system to help identify people at highest risk because it better describes the tumor size and degree of invasion and the number of lymph nodes involved. The staging system is described in detail in the treatment section.
