Determining the Grade of the Tumour
Pathologists will typically report on the grade of the tumour. This is a qualitative interpretation by the pathologist of how much the cancerous cells resemble normal tissue from that site. There are several different grading systems that might be used.

The most common system is as follows:
 GX: Grade cannot be assessed
 G1: Well differentiated
 G2: Moderately differentiated
 G3: Poorly differentiated
 G4: Undifferentiated

Differentiation refers to how closely the cells taken from a tumour or lesion resemble normal cells from the healthy tissue surrounding the tumour. “Well differentiated” means that the cells look like normal cells in that area. “Undifferentiated” means the cells look nothing like normal cells in that area.

While it is important to report the tumour’s grade, few doctors use this information to make decisions regarding treatment or prognosis for this cancer type.

Determining the Stage of the Cancer
The final step before discussing treatment options is a determination of the stage of the cancer. As with all cancers of the head and neck, in Australia it is mandatory for doctors to use the AJCC Cancer Staging Manual (7th Ed) to determine the stage based on three factors.

Factors that go into determining the stage of the cancer
T Characteristics of the main tumour mass
N Status of the lymph nodes in the neck (i.e., evidence of cancer spread)
M Status of cancer spread to parts of the body outside of the head and neck

At first, you will be given a clinical stage based on all the available information.

Clinical staging (cTNM) is determined from any information your doctor might have about how extensive the cancer is BEFORE starting any treatment. Stage is determined based on your doctor’s physical exam, imaging studies, laboratory work and biopsies. Classification of clinical stage is described using the lowercase prefix c (e.g., cT, cN, cM).

If there is surgical removal of the cancer as part of your treatment, a pathologist will analyze the tumour and any lymph nodes that may have been removed. You will then be assigned a pathologic stage.

Pathologic staging (pTNM) provides more data. Classification of pathology stage is described using the lowercase prefix p (e.g., pT, pN, pM). This may or may not differ from the clinical stage.

There are also several other lowercase prefixes that might be used in the staging of your cancer.
 The subscript y (yTNM) is used to assign a cancer stage after some sort of medical, systemic or radiation treatment is given (Posttherapy or Postneoadjuvant Stage). It is typically combined with either a clinical or pathologic stage. For example, ycT2N0M0 indicates that after some sort of non-surgical therapy, the new clinical stage is T2N0M0.
 The subscript r (rTNM) is used when the tumour has recurred after some period of time in which it was gone. This is called Retreatment Classification Stage. Your doctor will use all the available information to assign you a retreatment stage.

T stage: the main tumour mass
Based on a physical examination and review of any imaging, your doctor should be able to give you a T stage that falls within one of the following categories.

Tx The doctor is unable to assess the primary tumour.
T0 The doctor is unable to find the primary tumour.
Tis Carcinoma in situ (or severe dysplasia); this means there are cancer type cells, but they have not yet invaded deep into tissue. This is more of a pre-cancer lesion.
T1 The tumour is 2 centimetres or less in greatest dimension.
T2 The tumour is more than 2 centimetres but less than or equal to 4 centimetres in greatest dimension.
T3 The tumour is more than 4 centimetres in greatest size or has grown into the tongue side of the epiglottis.
T4a This is moderately advanced local disease. The tumour has grown into the larynx, the outside the tongue muscles, the hard palate, the lower jawbone and/or the medial pterygoid muscles.
T4b This is very advanced local disease. The tumour has invaded into the lateral pterygoid muscle, the pterygoid plates, up to the sides of the nasopharynx, into the skull base or completely around the carotid artery.

* Note that a little extension to the lingual surface of the epiglottis from a base of tongue tumour does not constitute spread into the larynx.

N stage: spread of cancer to the lymph nodes in the neck
Next, your doctor will use all the available information and assign you an N stage. This is based on the assessment as to whether the cancer has spread to lymph nodes in the neck.

Nx The neck lymph nodes cannot be assessed.
N0 There is no evidence of any spread to the nodes.
N1 There is a single node, on the same side of the main tumour, that is 3 centimetres or less in greatest size.
N2a Cancer has spread to a single lymph node, on the same side as the main tumour, and it is more than 3 centimetres but less than or equal to 6 centimetres in greatest dimension.
N2b There are multiple lymph nodes that have cancer, on the same side as the main tumour, but none are more than 6 centimetres in size.
N2c There are lymph nodes in the neck on either the opposite side as the main cancer, or on both sides of the neck, but none are more than 6 centimetres.
N3 There is spread to one or more neck lymph nodes, and the size is greater than 6 centimetres.

M stage: spread of cancer outside the head and neck
Finally, based on an assessment on the entire body, you will be assigned an M stage.

M0 No evidence of distant (outside the head and neck) spread.
M1 There is evidence of spread outside of the head and neck (i.e., in the lungs, bone, brain, etc.).

Your cancer stages
After TNM staging, your doctor can assign a cancer stage based on the following chart.

Stage I T1 N0 M0
Stage II T2 N0 M0
Stage III T3 N0 M0
T1 N1 M0
T2 N1 M0
T3 N1 M0
Stage IVA T4a N0 M0
T4a N1 M0
T1 N2 M0
T2 N2 M0
T3 N2 M0
T4a N2 M0
Stage IVB T4b Any N M0
Any T N3 M0
Stage IVC Any T Any N M1

Your clinical stage
Once the diagnostic tests are completed, before deciding what type of treatment you are going to undergo, you should be given a clinical stage that will look like the example below.

CLINICAL STAGE
Example
Site Oropharynx
Subsite Base of Tongue
Type Squamous Cell Carcinoma
cT cT3
cN cN1
cM cM0
cStage cIII

* The lowercase subscript c indicates that this is a CLINICAL STAGE, the stage assigned based on all information available to your doctor before starting treatment.

After surgery, you should get a pathologic stage of your tumour. It will look almost like the clinical stage you received before starting treatment, but notice the “p” that indicates the stage group is based on an analysis of the entire tumour, with or without lymph nodes, under a microscope by a pathologist. In many cases, the pathologic stage will be the same as the clinical stage, but sometimes it will change.

After surgery, and after the pathologist has evaluated all the tumour that was removed, you should be given a pathologic stage that looks something like this:

PATHOLOGIC STAGE
Example
Site Oropharynx
Subsite Base of Tongue
Type Squamous Cell Carcinoma
pT pT3
pN pN2b
cM cM0
pStage pIVa

*The lowercase subscript p indicates that this is a PATHOLOGIC STAGE, the stage assigned after tumour removal and confirmation of cancer by a pathologist.

*Note also that the M stage is usually clinical, based on all available data without analysing any tissue.