The stage of a cancer is determined by the TNM staging system:
- The ‘T’ stands for tumour size.
- The ‘N’ stands for lymph node involvement.
- The ‘M’ stands for distant metastases, or cancer spread to other areas of the body.
Staging helps doctors determine how serious the cancer is and how best to treat it. For well-differentiated thyroid cancers (such as papillary thyroid carcinoma and follicular thyroid carcinoma), the staging is determined based on the patient’s age, with different staging systems for patients under and over 55 years of age.
|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 of 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 analyse the tumour and any lymph nodes that may have been removed. You will then be assigned a pathological stage.
Pathological 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 (Post therapy or Post neoadjuvant Stage). It is typically combined with either a clinical or pathological 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 Re-treatment Classification Stage. Your doctor will use all the available information to assign you a re-treatment stage.