What do doctors mean by T, N, and M?

This system was first proposed by Frenchman Pierre Denoix, and was later gradually improved by the American Joint Committee on Cancer (AJCC) and the International Union Against Cancer (UICC). The first edition of the "TNM Classification of Malignant Tumors" manual was officially published in 1968. Today, TNM staging has become one of the standard tools for clinicians and medical scientists.

TNM is the acronym for Tumor, Node, and Metastasis. Let's take a look at what these three letters stand for:

1. T (Tumor): refers to the condition of the primary tumor, including the size of the tumor and the extent of involvement of the adjacent tissues of the tumor, expressed as T1 to T4. The larger the T, the larger the "territory" of the tumor;

2. N (Node): refers to the involvement of regional lymph nodes. When lymph nodes are not involved, it is represented by N0. As the degree and range of lymph node involvement increase, it is represented by N1 to N3. The larger the N, the more "helpers" the tumor has;

3. M (Metastasis): refers to distant metastasis (usually spread through blood). M0 is used to represent those without distant metastasis, and M1 is used to represent those with distant metastasis. M1 means that the tumor's "expeditionary army" has set out.

The "secret code" of TNM staging

The TNM staging system for each tumor is different, so the meaning of the letters and numbers in the TNM staging is different for different tumors. After T, N, and M in the TNM staging are determined, the corresponding overall clinical stage can be obtained, namely stage I, stage II, stage III, stage IV, etc. Sometimes, in order to staging more accurately, it is sometimes subdivided into IIa or IIb, etc. with letter combinations. Different stages have different treatment methods and different clinical prognoses. Stage I tumors usually have a relatively better prognosis than early tumors. A higher stage means a higher degree of tumor progression and a worse prognosis. In clinical applications, the TNM staging standards for each tumor are slightly different.

Clinical significance of TNM staging symbols

TX: The primary tumor cannot be assessed

T0: No evidence of a primary tumor

Tis: Early stage tumor has not spread to adjacent tissues, which is equivalent to the "budding state"

T1-4: size and/or extent of the primary tumor. The larger the T, the larger the tumor's "territory"

NX: Regional lymph node status cannot be assessed

N0: No regional lymph node involvement (no tumor found in the lymph nodes), equivalent to "fighting alone"

N1: Only a few lymph nodes near the tumor are affected

N2: A condition between N1 and N3 (not applicable to all tumors)

N3: Distant and/or additional lymph nodes are involved (not applicable to all tumors)

M0: No distant metastasis (the cancer has not spread to other parts of the body)

M1: Distant metastasis (tumor spread to organs or parts of the body)

The significance of TNM staging

l Unified standards can relatively accurately determine the patient's tumor stage before diagnosis and treatment, help doctors determine the severity of the tumor and choose appropriate treatment, and can accurately predict the prognosis.

l Make treatments homogenized and standardized to improve the country's overall level of cancer diagnosis and treatment.