Number stages and grades of mouth cancer

About staging

There are different ways of staging mouth cancer. These are the number staging system and the TNM system.

The Number staging system divides mouth cancer into 4 main stages, from 1 to 4. Stage 1 is an early cancer and stage 4 is an advanced cancer. Some doctors also use stage 0. 

Doctors might also use the TNM staging system.

Find out about the TNM staging system

Doctors stage mouth cancers differently from cancers that start in the throat behind the mouth (oropharyngeal cancer).

Find out about staging oropharyngeal cancers

How do doctors find out your stage?

There are different ways to find out your stage. Your doctor might use:

• clinical staging before treatment and if you don't have surgery

• pathological staging if you do have surgery

Clinical staging

This means the doctor stages you after examining you and looking at test and scan results. Doctors use clinical staging to plan your treatment. It’s also the best way to stage people who aren’t having surgery. You might see your clinical stage written as cTNM.

Pathological staging

This means the doctor stages you after examining the tissue that the surgeon removes during an operation. This is also called surgical staging. The doctors combine your clinical stage results with the surgical results. Pathological staging is generally a more precise way to find out how far your cancer has spread. Your pathological stage might be different to your clinical stage. You might see your pathological stage written as pTNM.

Pathological staging is different from clinical staging for mouth cancer. For example, pathological staging looks at the number of lymph nodes containing cancer rather than their size.

We describe the clinical stage below. This is because not everyone with mouth cancer has surgery to stage their cancer, so doctors don't always know the pathological stage.  

Cancer staging is complicated, so if you need help understanding it, ask your doctor or specialist nurse to explain it to you.

Stage 0 or carcinoma in situ (CIS)

Stage 0 cancer or carcinoma in situ (CIS) means your cancer is at a very early stage. Some doctors prefer to call this pre cancer. There are cancer cells but they are all contained within the lining of the mouth. The cancer cells have not spread.

If the pre cancer is not treated, there is a high risk the condition will develop into an invasive cancer. 

In the TNM staging system stage 0 mouth cancer is the same as Tis, N0, M0.

Stage 1

This is the earliest stage of invasive cancer. 

It means the cancer is 2cm or smaller and it is 5mm deep or less. It has not spread to nearby tissues, lymph nodes or other organs.

In the TNM staging system, stage 1 mouth cancer is the same as T1, N0, M0.

Stage 2

Stage 2 can mean one of the following:

• the cancer is 2cm or smaller, and it is deeper than 5mm but no deeper than 10mm

• the cancer is larger than 2cm but no larger than 4cm, and it is 10mm deep or less

The cancer has not spread to nearby lymph nodes or other organs.

In the TNM staging system, stage 2 mouth cancer is the same as T2, N0, M0

Stage 3

Stage 3 can mean one of the following;

• the cancer is larger than 4 cm but has not spread to nearby lymph nodes or other organs

• the cancer is any size. It has grown deeper than 10mm but no deeper than 20mm. One lymph node contains cancer cells on the same side of the neck as the cancer. The node is no larger than 3cm across. The cancer has not spread into the tissue surrounding the lymph node or to other organs

In the TNM staging system, stage 3 mouth cancer is the same as one of the following:

• T3, N0, M0

• T1 - 3, N1, M0

Stage 4

Stage 4 means the cancer is advanced. It is further divided into 3 stages - 4a, 4b and 4c.

Stage 4a 

Stage 4a can mean one of the following:

• the cancer has grown further than the mouth and into surrounding structures such as the jaw bones, the skin of the face or the facial air filled cavities spaces in the skull (sinuses) or the tongue. One lymph node may contain cancer cells on the same side of the neck as the cancer. The node is no larger than 3cm across. The cancer has not spread into tissue surrounding the lymph node or other organs

• the cancer is any size or depth. It has spread into one or more lymph nodes on one or both sides of the neck. The lymph nodes are between 3 and 6cm in size. The cancer has not spread into the tissue surrounding the lymph node or other organs

In the TNM staging system, stage 4a mouth cancer is the same as one of the following:

• T4a, N0 - 1, M0

• T1 - 4a, N2, M0

Stage 4b

Stage 4b can mean one of the following:

• the cancer is any size or depth. One lymph node contains cancer cells and is larger than 6cm across. The cancer has not spread into tissues surrounding the lymph node. Or any number of lymph nodes contain cancer and have spread into tissues surrounding the lymph node. The cancer has not spread to other organs

• the cancer has spread into nearby areas, such as the space behind the jaw, other nearby bones, the base of the skull or the tongue, or has surrounded a large blood vessel called the carotid artery. Any number of lymph nodes may contain cancer cells, they may be any size, on one or both sides of the neck and the cancer may have spread into the tissues surrounding the lymph node. The cancer has not spread to other organs.

In the TNM staging system, stage 4b mouth cancer is the same as one of the following:

• any T, N3, M0

• T4b, any N, M0

Stage 4c

Stage 4c means the cancer has spread to other parts of the body such as the lungs or bones.

In the TNM staging system, stage 4c mouth cancer means:

• any T, any N, M1

Grades of mouth cancer

The grade of a cancer tells you how much the cancer cells look like normal cells. This gives your doctor an idea of how the cancer might behave and what treatment you need. 

There are 3 grades of mouth cancer:

• grade 1 (low grade) means the cancer cells look like normal mouth cells

• grade 2 (intermediate grade) means the cancer cells look slightly different to normal mouth cells

• grade 3 (high grade) means the cancer cells look very abnormal and not much like normal mouth cells 

Your cancer might be graded as Gx. This means that the grade cannot be assessed.

Differentiation

Differentiation means how developed or mature a cell is. Doctors might describe cancer as poorly or well differentiated. 

Doctors might describe:

• grade 1 cancer as well differentiated

• grade 2 cancer cells are moderately differentiated

• grade 3 cancer cells are poorly differentiated

Treatment

The stage of your cancer helps your doctor to decide which treatment you need. Treatment also depends on:

• your type of cancer (the type of cells the cancer started in)

• where the cancer is

• other health conditions that you have

Treatment might include:

• ​surgery​

• ​radiotherapy​ or ​chemoradiotherapy​ after surgery

• ​chemotherapy​

• a ​targeted cancer drug​

• ​immunotherapy​

If you have early stage lip cancer, you may have surgery or radiotherapy as your main treatment.

Find out more about treatment