How does the TNM staging system describe lung cancer?

The TNM staging system is an internationally standardized protocol used to describe the extent and dissemination of cancer, including lung cancer. It provides a structured way to assess how far a tumor has spread within the body, which is essential for determining a patient's prognosis and selecting the most appropriate treatment approach.1

The system is defined by three primary components:

• T (Tumor): Describes the size and local extent of the primary tumor.1
• N (Node): Indicates the presence and extent of lymph node involvement or metastases.1
• M (Metastasis): Denotes whether the cancer has spread to distant sites in the body.1

By evaluating these three factors, clinicians can classify the stage of the disease, which remains independent of the tumor's histological grade—a separate measure that assesses the aggressiveness of the cancer based on tissue structure and differentiation.1