That is, it looks at the tumor and the extent to which it has spread to other parts of the body. Once doctors know how far along the cancer is, they can decide on the best course of treatment. The staging of colon cancer is relatively straightforward. The tumor penetrates into the mucosa of the bowel wall but no further.
Tumor invades muscularis propria.
Tumor invades through the muscularis propria into the subserosa, or into the pericolic or perirectal tissues. No regional lymph node metastasis. Metastasis in 1 to 3 regional lymph nodes. Metastasis in 4 or more regional lymph nodes. No distant metastasis.