What do T, N, and M mean in the TNM cancer staging system?

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The TNM staging system is an internationally standardized method used to describe the extent and spread of cancer, including lung cancer. It provides critical information for determining a patient's prognosis and selecting the most appropriate treatment approach.1

In this system, the letters represent the following criteria:

T: Refers to the size and extent of the primary tumor.1
N: Indicates the presence and extent of lymph node involvement or metastases.1
M: Denotes whether the cancer has spread, or metastasized, to distant parts of the body.1

By evaluating these three factors, clinicians can accurately determine the stage of the disease, which is essential for effective clinical decision-making.1