Determining the Grade of the Tumour

Squamous cell cancers of the oral cavity are typically given a grade by a pathologist after looking at the cells under a microscope. Grade means that the tumour falls on a scale from well differentiated (Grade I) to poorly differentiated (Grade IV). Even though there are some studies that show grade is important in predicting outcome, as of now, grade does not really factor heavily into most doctors’ treatment decisions, nor your prognosis. Determining the Stage of the Cancer The final step before discussing treatment options is a determination of the stage of the cancer. 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 lower-case prefix c (e.g., cT, cN, cM). If there is surgical removal of the cancer as part of your treatment, a pathologist will analyse 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 lower-case prefix p (e.g., pT, pN, pM). This may or may not differ from the clinical stage. There are also several other lower-case 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 dimension.
T4a This is moderately advanced local disease. The tumour clearly invades into the skin of the face, through the upper or lower jawbone, into the nerve that allows you to feel the teeth and chin area or into the floor of the mouth. Note: A little bit of bone or tooth socket invasion from a tumour of the gums does NOT make it a T4a cancer.
T4b This is very advanced local disease. This stage is assigned if the tumour is invading into the masticator space, pterygoid plates, base of the skull and/or encases the carotid artery.
 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 0 Tis N0 M0
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 Any T N3 M0
T4b Any N 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 Oral Cavity
Subsite Floor of Mouth
Type Squamous Cell Carcinoma
cT cT4a
cN cN2b
cM cM0
cStage cIVa
 * The lower-case 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. You should consider the pathologic stage to be a more accurate assessment of your tumour at the time you start treatment. 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 Oral Cavity
Subsite Floor of Mouth
Type Squamous Cell Carcinoma
pT pT4a
pN pN2b
cM cM0
pStage pIVa
 * The lower-case subscript p indicates that this is a PATHOLOGIC STAGE, the stage assigned after tumour removal and confirmation of cancer by a pathologist.