Find out what the TNM staging system is, and how it is used for nasopharyngeal cancer.
What staging is
The stage of a cancer tells you where it is, how big it is and whether it has spread. This helps your doctor decide which treatment you need.
What TNM means
Doctors use a staging system called TNM. The letters stand for tumour, node and metastasis:
- T describes the size of the tumour
- N describes whether there are any cancer cells in the lymph nodes
- M describes whether the cancer has spread to a different part of the body
T stages describe the size of your primary tumour.
T0 means that there is no evidence of a tumour. TIS (tumour in situ) means there are cancer cells only in the surface layer of the nasopharynx. Doctors also call this carcinoma in situ (CIS). It is a very early stage cancer.
There are 4 main T stages of nasopharyngeal cancer.
T1 means the cancer is contained within the nasopharynx, or it has spread into the area at the back of the mouth and top of the throat (oropharynx) or the nasal cavity.
T2 means cancer cells have spread into areas next to the nasopharynx. But they have not spread into bone. You might hear this called parapharyngeal extension.
T3 means the tumour has spread into the sinuses or the bones near the nasopharynx.
T4 means the tumour has spread into one or more of the following areas:
- the cranial (skull) nerves (these nerves are close to the nasopharynx and control our eye movement, sight and sense of smell)
- the lower part of the throat (hypopharynx)
- the eye or the surrounding tissue
- the bony spaces near the cheek and teeth
N stages describe whether the cancer has spread to any lymph nodes, and the size and position of any nodes affected. There are 4 main N stages of nasopharyngeal cancer.
N0 means there are no lymph nodes containing cancer cells
N1 means there are cancer cells in one or more lymph nodes on one side of the neck, or there are cancer cells in the lymph nodes behind the throat on one or both sides of the neck. But in either case, the nodes are not more than 6cm across
N2 means there are cancer cells in lymph nodes on both sides of the neck. The nodes are not more than 6cm across and are above the collarbone.
N3 is divided into 3a and 3b:
- N3a means there are cancer cells in one or more lymph nodes, and one affected node is more than 6cm across
- N3b means there are cancer cells in the dip above the collarbone, called the supraclavicular fossa
M stages describe whether the cancer has spread to another part of your body. There are just 2 M stages to describe spread of nasopharyngeal cancer:
- M0 means the cancer has not spread to other parts of the body
- M1 means the cancer has spread to other parts of the body
Number staging system
Together, the T, N and M stages give your doctor a complete description of the stage of your cancer.
For example, if your cancer has the stages T1, N0 and M0, you might have a tumour that has spread beyond the nasopharynx into the nasal cavity or oropharynx. But the cancer has not spread to your lymph nodes or to any other parts of your body.
The different combinations of T, N and M stages are then grouped together to give 4 main number stages.
The stage of your cancer helps your doctor to decide which treatment you need. Your treatment also depends on:
- the type of cancer (the type of cells the cancer started in)
- the grade of cancer (how much the cells look like normal cells)
- where the cancer is
- other health conditions that you have