Knowing the stage of the disease helps the doctor to plan treatment. The following stages are used for colorectal cancer:

Stage 0 
The cancer is in the earliest stage. It has not grown beyond the inner layer (mucosa) of the colon or rectum. This stage is also known as carcinoma in situ or intramucosal carcinoma.

Stage I
The cancer has grown through the inner layers of the colon or rectum but not the outermost layers. It has not spread to nearby lymph nodes or distant sites.

Stage II
The cancer has grown into the outermost layers of the colon or rectum but not yet spread to the nearby lymph nodes or distant sites.

Stage III
The cancer has spread to one or more lymph nodes in the area but not to the distant sites.

Stage IV
The cancer has spread to other parts of the body, such as the liver, lung, or bones. This stage does NOT depend on how deep the tumour has penetrated or if the disease has spread to the lymph nodes near the tumor.



  Stages: Adapted from National Cancer Institute 

Updated:: 13/03/2019 []