Staging is a term that describes how advanced a cancer is at the time of diagnosis. The stage provides an estimation of the severity of the cancer. Knowing the stage of the cancer is important so that the doctor can better design a personalized treatment plan for you.
The most commonly used staging systems are the TNM Staging System and Stage Grouping.
TNM Staging System
TNM Staging describes different kinds of tumours. Letters and numbers are used to describe the type of cancer in detail.
Tumour (T): The “T” stage describes the size of the original tumour and how far into nearby tissue the tumour has spread.
TX means that no tumour can be clinically assessed.
T0 means that no tumour is present.
Tis means that a tumour may be developing.
T1, T2, T3, and T4 indicate the size of the first tumour developed.
Node (N): The “N” stage describes how far the cancer has spread in the lymph nodes. Lymph nodes are structures in the immune system that contain infection-fighting cells.
NX means that the lymph nodes cannot be clinically assessed.
N0 means that no nearby lymph nodes are involved.
N1, N2, and N3 indicate the amount and location of lymph nodes that are involved.
Metastasis (M): The “M” stage describes how far into other body parts the cancer has spread.
MX means that cancer that has spread to other body parts cannot be clinically assessed.
M0 means that the cancer has not spread to other body parts.
M1 means that the cancer has spread to other body parts.
For example, lung cancer staged “T3 N2 M0” means that there is a large tumour in the lungs that has spread to nearby lymph nodes, but has not spread to body parts further away.
Once the TNM stage of cancer has been determined, the doctor assigns the cancer to one of four stage groups to describe the cancer’s development.
Stage 0: Cancer is controlled within the area where the tumour started and has not spread.
Stage 1 and 2: Cancer may begin to spread to nearby tissue.
Stage 3: Cancer has spread to nearby lymph nodes.
Stage 4: Cancer has spread to distant body parts.