Stages and grades of oropharyngeal cancer
Oropharyngeal cancer starts in the oropharynx, which is the part of the throat just behind the mouth. It includes cancer that starts in the back of the tongue and tonsil cancer.
The stage of your oropharyngeal cancer tells you how big it is and whether it has spread. The grade means how abnormal the cancer cells look under the microscope.
Some oropharyngeal cancers contain a virus called HPV. Doctors stage oropharyngeal cancer that contains HPV in a different way to oropharyngeal cancers that don't contain HPV.
Doctors also stage oropharyngeal cancer differently to cancers that start in the mouth.
Staging systems
Doctors use different systems to stage oropharyngeal cancer.
Your doctor might use the TNM system. This system describes:
- the size of the primary tumour (T)
- whether the cancer has spread to the lymph nodes (N)
- whether the cancer has spread to another part of the body (M)
Or the doctors might use a number staging system of 1 to 4.
Staging and human papilloma virus (HPV)
The doctor tests oropharyngeal cancer cells for a virus called human papilloma virus (HPV):
- HPV positive cancers contain HPV
- HPV negative cancers don’t contain HPV
People with HPV positive oropharyngeal cancers tend to have a better outlook than people with HPV negative oropharyngeal cancers. The way doctors stage HPV positive oropharyngeal cancers is different to how they stage HPV negative 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 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 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.
For oropharyngeal cancer, the pathological staging is different from clinical staging. For example, pathological staging looks at how many lymph nodes contain cancer, rather than the size of the lymph nodes.
In the sections below we describe the clinical stage. This is because not everyone with oropharyngeal cancer has surgery to stage their cancer, so doctors don't always know the pathological stage.
Cancer staging is complicated so ask your doctor or specialist nurse to explain this to you if you need help to understand it.
Staging and grading HPV positive oropharyngeal cancer
HPV positive oropharyngeal cancers contain the human papilloma virus (HPV). Your doctor might describe your cancer stage using the TNM staging system or the number staging system.
T (tumour)
T describes the size of the tumour (area of cancer).
There are 4 main T stages of HPV positive oropharyngeal cancer. These are T1 to T4.
T1 means the tumour is 2cm or smaller.
T2 means the tumour is larger than 2cm, but no larger than 4cm.
T3 means one of the following:
- the cancer is larger than 4cm
- the cancer has spread into the flap of tissue (epiglottis) at the top of the voice box (larynx)
T4 means the cancer has spread into nearby areas, such as the voice box (larynx), the jawbone (mandible), or muscles connecting the tongue to the jawbone (extrinsic muscles).
Node (N)
N refers to your lymph nodes. These are a network of glands throughout the body, for example in your armpits and neck. They drain away waste fluid, waste products and damaged cells, and contain cells that fight infection.
The important points here are:
- whether any nodes contain cancer
- the size of the node containing cancer
- which side of the neck the node containing cancer is on
N0 means the lymph nodes don’t contain cancer cells.
N1 means that one or more lymph node contains cancer cells on the same side of the neck as the cancer. None of the nodes are larger than 6cm.
N2 means there are cancer cells in lymph nodes on the opposite side of the neck to the cancer, or on both sides. None of these nodes are larger than 6cm.
N3 means at least one lymph node is bigger than 6cm.
Metastasis (M)
M describes whether the cancer has spread to a different part of the body.
There are 2 main stages - M0 and M1.
M0 means the cancer has not spread to other parts of the body
M1 means cancer has spread to other parts of the body such as the lungs
There are 4 main stages in this system (stage 1 - 4).
Stage 1
The cancer is 4cm or smaller. The lymph nodes might contain cancer cells on the same side of the neck as the cancer. None of the nodes are larger than 6cm.
In the TNM staging system stage 1 is the same as T1 or 2, N0 or 1, M0.
Stage 2
Stage 2 means one of the following:
- the cancer is 4cm or smaller and there are cancer cells in lymph nodes on the opposite side of the neck to the cancer, or on both sides, but none are larger than 6cm
- the cancer is larger than 4cm, or the cancer has spread into the flap of tissue (epiglottis) at the top of the voice box (larynx), and the lymph nodes may contain cancer but none are larger than 6cm
In the TNM staging system stage 2 is the same as one of the following:
- T1 or 2, N2, M0
- T3, N0, 1 or 2, M0
Stage 3
Stage 3 means one of the following:
- the cancer is any size, and the lymph nodes contain cancer and at least one lymph node is bigger than 6cm
- the cancer has spread into nearby areas, such as the voice box (larynx), jawbone (mandible), or muscles connecting the tongue to the jawbone (extrinsic muscles) and it may have spread to the lymph nodes
In the TNM staging system stage 3 cancer is the same as one of the following:
- Any T, N3, M0
- T4, any N, M0
Stage 4
Stage 4 means the cancer is advanced. The cancer has spread to other parts of the body such as the lungs.
In the TNM staging system stage 4 cancer means any T, any N, M1.
The grade of a cancer tells you how much the cancer cells look like normal cells. Doctors don't grade HPV positive oropharyngeal cancers.
Staging and grading HPV negative oropharyngeal cancer
HPV negative oropharyngeal cancers do not contain the human papilloma virus (HPV). Your doctor might describe your cancer stage using the TNM staging system or the number staging system.
T (tumour)
T describes the size of the tumour (area of cancer).
There are 5 main T stages of HPV negative oropharyngeal cancer. These are Tis to T4.
Tis means the cancer cells are all contained within the lining of the oropharynx. It is also called cancer in situ.
T1 means the tumour is 2cm or smaller.
T2 means the tumour is larger than 2cm, but no larger than 4cm.
T3 means one of the following:
- the cancer is larger than 4cm
- the cancer has spread into the flap of tissue (epiglottis) at the top of the voice box (larynx)
T4 is split into 2 groups - T4a and T4b.
T4a means the cancer has spread into nearby areas, such as the voice box (larynx), the jawbone (mandible), or muscles connecting the tongue to the jawbone (extrinsic muscles). This is also called moderately advanced local disease.
T4b means the cancer has spread into nearby areas such as the base of the skull, or the area of neck surrounding the arteries (carotid arteries). This is also called very advanced local disease.
Node (N)
N refers to your lymph nodes. These are a network of glands throughout the body, for example in your armpits and neck. They drain away waste fluid, waste products and damaged cells, and contain cells that fight infection.
The important points here are:
- whether any nodes contain cancer
- the size of the node containing cancer
- which side of the neck the node containing cancer is on
- whether the cancer has spread into the tissue surrounding a lymph node (extranodal extension or ENE)
N0 means the lymph nodes don’t contain cancer cells.
N1 means that 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 tissue surrounding the lymph node.
N2 is split into 3 groups - N2a, N2b and N2c.
N2a means one lymph node contains cancer cells on the same side of the neck as the cancer. The node is between 3 cm and 6 cm across. The cancer has not spread into tissue surrounding the lymph node.
N2b means that more than one lymph node contains cancer cells on the same side of the neck as the cancer. None of these nodes are more than 6cm across. The cancer has not spread into tissue surrounding the lymph node.
N2c means there are cancer cells in lymph nodes on the other side of the neck to the cancer, or in nodes on both sides of the neck. None of these nodes are more than 6cm across. The cancer has not spread into tissue surrounding the lymph node.
N3 is split into 2 groups - N3a and N3b.
N3a means that one lymph node containing cancer cell is larger than 6cm across. The cancer has not spread into tissues surrounding the lymph node.
N3b means any number of lymph nodes contain cancer cells. The cancer has spread into tissues surrounding a lymph node.
Metastasis (M)
M describes whether the cancer has spread to a different part of the body.
There are 2 main stages - M0 and M1.
M0 means the cancer has not spread to other parts of the body
M1 means cancer has spread to other parts of the body such as the lungs
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 oropharynx. 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.
Stage 1
This is the earliest stage of invasive cancer.
It means the cancer is 2cm or smaller. It has not spread to nearby tissues, lymph nodes or other organs.
In the TNM staging system stage 1 cancer is the same as T1, N0, M0.
Stage 2
Stage 2 means the cancer is larger than 2cm but no larger than 4cm. It has not spread to nearby lymph nodes or other organs.
In the TNM staging system stage 2 cancer is the same as T2, N0, M0
Stage 3
Stage 3 means one of the following;
- the cancer is larger than 4cm or has spread into the flap of tissue (epiglottis) at the top of the voice box (larynx), but it has not spread to any lymph nodes or to other parts of the body
- the cancer is any size but one lymph node contains cancer cells on the same side of the neck as the cancer - the lymph node is no more than 3cm across and it hasn't spread into the tissue surrounding the node
In the TNM staging system stage 3 cancer is the same as one of the following:
- T3, N0, M0
- T1,2 or 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 different things, including:
- the cancer has grown further than the oropharynx into nearby areas such as the voice box (larynx) or jawbone (mandible)
- cancer has spread to lymph nodes on either side of the neck, which are between 3 and 6 cm in size
In the TNM staging system stage 4a cancer is the same as one of the following:
- T4a, N0 or 1, M0
- T1,2,3 or 4a, N2, M0
Stage 4b
Stage 4b can mean different things, including:
- cancer has spread into nearby areas such as the base of the skull, or the area of neck surrounding the arteries (carotid arteries)
- a lymph node containing cancer is larger than 6cm
- cancer has spread into tissues surrounding a lymph node
In the TNM staging system stage 4b 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 cancer means:
- any T, any N, M1
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 4 grades of HPV negative oropharyngeal cancer:
- grade 1 (low grade) look very much like normal oropharyngeal cells
- grade 2 (intermediate grade) look slightly different to normal oropharyngeal cells
- grade 3 (high grade) look very abnormal and not much like normal cells
- grade 4 (high grade) look very different to normal oropharyngeal cells
Differentiation means how developed or mature a cell is. Doctors might describe cancer as poorly or well differentiated.
So doctors may describe:
- grade 1 cancer as well differentiated
- grade 2 cancer cells as moderately differentiated
- grade 3 cancer cells as poorly differentiated
- grade 4 cancer cells as undifferentiated
Your cancer might be graded as Gx. This means that they cannot assess the grade.
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
The stage of the cancer and these other factors can also give an idea of your outlook (prognosis).
Treatment might include:
- surgery
- radiotherapy
- chemotherapy
