Diagnosed with Colorectal Cancer?
Finding out more about CRC, what stage you are at and what the first steps are to consider.
Identifying Risk Factors
How Bad Is It?
After being diagnosed with colorectal cancer doctors will ‘rate’ the extent of the cancer. This system is called staging.
The stage of a cancer describes how much cancer is present in the body and where it is located. It helps determine how serious the cancer is and which treatments are best. Doctors also use a cancer’s stage when talking about survival statistics.
Scoring and Staging of Colorectal Cancer
The clinical staging of colorectal cancer is based on the results of radiological, biochemical and endoscopic tests and is done before surgery or treatment.
It guides the decision to optimal treatment of colorectal cancer with or without surgery.
When trying to determine the extent of the cancer in the body clinicians first look at the primary (main) tumour for its size, location and whether it has grown into nearby areas.
They might also look at nearby lymph nodes to find out if cancer has spread into them. Lymph nodes are small, bean-shaped collections of immune cells. Many types of cancer often spread to nearby lymph nodes before they reach other parts of the body.
Doctors might also look at other parts of the body to see if the cancer has spread there. When cancer spreads to parts of the body far from the primary tumour it is known as metastasis.
The staging system most often used for colorectal cancer is the American Joint Committee on Cancer (AJCC) TNM system, where the three letters T, N and M describe the areas of cancer growth.
A number after T,N and M (0-4) will describe size and/or amount of spread into nearby structures, nodes or organs. The higher the number, the larger the tumour and/or the more it has grown into or spread to nearby tissues or organs.
Once the values for T, N, and M have been determined, they are combined to assign an overall stage.
For most cancers, the stage is a Roman numeral from I to IV, where stage IV (4) is the highest.
As a rule, the lower the number, the less the cancer has spread. A higher number such as stage IV means cancer has spread more. And within a stage an earlier letter means a lower stage. So the stage determines the prognosis: the lower the stage the better the prognosis.
The stage is fundamental in order to make the right decision about the treatment.
During surgery the primary tumour and its locoregional lymph nodes are removed.
After examination of this resection specimen under the microscope the pathologist will determine the pathological staging with an exact (final) interpretation of the depth of invasion into the bowel wall and the number of lymph nodes involved with the tumour.
The prognosis of colorectal cancer is clearly related to:
- The staging features of the TNM classification including the degree of penetration of the tumour through the bowel wall
- The presence, or absence, of nodal involvement
- The presence, or absence, of metastasis
The system in the link below is the most recent AJCC system effective January 2018.
Cancer staging can be complex, so ask your doctor to explain it to you in a way you understand.