Tumour Staging for Colorectal Cancer
If colorectal cancer is diagnosed, the next step will be to determine the size of the tumour and whether it has spread to other parts of the body. This process is known as tumour staging. Knowing the stage of cancer is important to determine the most appropriate colorectal cancer treatment.
TNM Staging System
The TNM staging system is the most widely used cancer staging system. In a colorectal cancer diagnosis, you are likely to see the cancer described by this staging system in the pathology report.
- T category describes the primary Tumour site.
- N category describes the involvement of cancer cells in the lymph Nodes near the colon.
- M category describes the presence of cancer beyond the colon and its adjacent tissues such as to organs like the lungs or liver (Metastases).
Tis. The cancer is confined to the innermost layer of the colon or rectum
N0. There is no spread to lymph nodes
T1. The cancer has grown through the first few layers of the colon or rectum
N1. Cancer is found in 1-3 lymph nodes
T2. The cancer has grown into the thick muscular layer of the colon or rectum
N2. Cancer is found in four or more lymph nodes
T3. The cancer has grown through the entire colon or rectum wall
M0. There is no spread of cancer to distant organ(s).
T4. The cancer has grown through the entire colon or rectum wall and into nearby tissue or organs
M1. Cancer is found in distant organ(s).
Number Staging System
This system uses the TNM system to divide cancers into stages.
Stage 1 (I) – The cancer is relatively small and contained within the organ it started in (T1-N0-M0 or T2-N0-M0)
Stage 2 (II) – Can be divided into stages 2A (T3-N0-M0), 2B (T4-N0-M0). The tumor is larger than in stage 1, but the cancer has not started to spread into the surrounding tissues. Sometimes stage 2 means that cancer cells have spread into lymph nodes close to the tumor.
Stage 3 (III) – Stage 3 can be divided into stages 3A (T1/2-N1-M0), 3B (T3/4-N1-M0), and 3C (any T-N1-M0), depending on where the tumor has grown and how many lymph nodes have cancer. Generally, the cancer is larger. It may have started to spread into surrounding tissues and there are cancer cells in the lymph nodes in the area
Stage 4 (IV) – The cancer has spread from where it started to another body organ (metastatic cancer). The cancer may be in only 1 organ or in distant lymph nodes (stage 4A). It may be in more than 1 organ (stage 4B). The cancer may be in the peritoneum (stage 4C) (any T-N-any N-M1).
