After all the test results have been examined, a final “pathologic” stage
will be assigned. Sometimes it’s a number and sometimes it’s a letter;
different staging systems are used in different places.
Stage 0 is also called carcinoma in situ. This is the earliest and
best diagnosis as the cancer is found only in the innermost lining of the
colon.
Stage I cancer has spread beyond the innermost lining of the colon
wall into the middle layers.
Stage II cancer is divided into stages IIA and IIB. With IIA the
cancer has spread beyond the middle tissue of the wall or spread to nearby
tissues around the colon or rectum. IIB has spread beyond the colon wall and
moved into nearby organs through the peritoneum (a transparent membrane that
lines the abdominal cavity).
Stage III cancer is divided into 3 sub-stages. With IIIA the cancer
has spread to the middle layers and 1-3 lymph nodes. The IIIB cancer has spread
to 1-3 lymph nodes AND beyond the middle tissue of the colon wall, or beyond
the wall into the organs, or to nearby tissues around the rectum or colon.
Stage IIIC has spread to 4 or more lymph nodes AND beyond the middle tissue, or
into the organs, or to nearby tissues around the rectum or colon.
Stage IV cancer is very advanced and carries the worst prognosis.
There is a 5-year survival rate of less than 5% for people diagnosed at this
late stage. Stage IV cancer has spread to other organs, often the liver, lungs,
or bones, and may have spread to lymph nodes as well.
Recurrent cancer is cancer that has returned after an initial
treatment.
In summary, Stage I indicates cancer in the most superficial layer of the
bowel wall, Stage II has moved into the muscular wall, Stage III indicates
cancer in the lymph nodes, Stage IV indicates spread to other sites, and
recurrent cancer has returned.