What is TNM staging?

In the previous article, we discussed about the procedure of  biopsy.This is followed by examination of the sample, and coming to a conclusion about the stage of cancer.This article talks about a very important aspect of Oncology, which is 'tumor staging'. It explains what tumor staging is, why is it essential, and how it's done.

What is 'tumor staging' ?
In simple words, tumor staging is system which shows the extent of malignancy in an individual.
In other words, it describes the stage of cancer.

What is the need for tumor staging?

• Tumor staging describes various aspects of the primary tumor, like, the anatomic involvement of structures, the size of tumor, the grade of tumor,spread to other regional sites like lymph nodes, and secondary tumor growth or metastasis.
• All the above mentioned aspects have to be known accurately in order to formulate a treatment protocol, and also establish a prognosis for an individual.
• On a wider scale, a standard tumor staging system is absolutely essential to be able to compare results of different treatments in different centers.
• Also, newer therapies can be evaluated by comparing them with the present therapies for the same stage of cancer.

stages of laryngeal cancer

What are the various tumor staging systems?

• The American Joint Committee on Cancer (AJCC) had recommended a staging system ranging from stage I (small, localized carcinoma ) to stage IV (distant metastatic spread). However, this is not widely used.
• The widely used system is called TNM staging system, as it gives more information about the tumor.

TNM staging:

• T stands for the primary tumor 
• N stands for the presence or absence of involvement of lymph nodes
• M stands for the presence or absence of distant metastases .

• After the T, increasing numerals like T1, T2, T3, or T4, indicate lesions of larger size that usually indicate a poor prognosis. 
• N0 indicates no spread to lymph nodes.
• N1 indicates spread to the lymph nodes. For more extensive nodal involvement, additional numbers can be used. 
• M0 indicates absence of metastasis
• M1 indicates presence of  distant metastasis. 

For example, There is a small lesion that has neither spread to regional nodes nor metastasized to distant sites.It would be designated as T1 N0 M0.
If there is a large lesion that involves the regional lymph nodes but not distant
sites may be identified as T2 N1 M0.
If there is a large neoplasm associated with both regional lymph nodes and distant metastases would be designated as  T3 N1 M1.

NOTE: For some tumors, a G for grade of malignancy is added.
Eg, soft tissue sarcoma.
High-grade tumors are less-differentiated and tend to metastasize sooner.


Classifications of the TNM system:
The TNM system is classified chronologically, or according to the time period when it is used.

• cTNM or TNM is also referred to as 'clinical classification'

This stands for the extent of cancer before the treatment began.
It is determined by results from physical examination, imaging studies, biopsy, endoscopy,exploratory surgery, etc.

• pTNM is the 'pathologic classification' 

It includes the information obtained during the pathological examination of tumor, or even during surgery.

• rTNM stands for 're-treatment classification'

It is used for staging the recurred cancer or relapse after a disease-free period of remission.
It includes some evidence of recurrence which maybe clinical or pathological.

• aTNM stands for 'autopsy classification"

This is based on a postmortem examination.


Also read
5 reasons why you should study Oncology.
Cancer and surgery.
What is Radiation oncology?
What is Cancer-related fatigue?
What is psycho-oncology?
12 causes of cancer.
Cancer in 21st century.