What is cancer staging?

After diagnosis, doctors need to know what ‘stage’ the disease is at. This information helps to understand how advanced the cancer is and will guide treatment options.

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Diagnostics - Helping doctors know the stage of a disease

Staging is determined by the size of the tumour, which lymph nodes  (if any) are affected, and whether the cancer has spread to other parts of the body (known as metastases or secondary cancer). The approach is sometimes known as TNM which stands for Tumour, Node and Metastasis.

Each of these three factors is given a number. The lower the numbers, the less advanced or smaller the cancer is. For example, a very small cancer which has not spread would be T1 N0 M0. These values are used to assign cancer to one of four categories:

Stage 1

The cancer is small and hasn’t spread (localised).

Stage 2 or 3


The cancer is larger and/or may have spread into surrounding tissues. There may be cancer cells in the lymph nodes (locally advanced).

Stage 4

The cancer has spread to another part of the body (metastatic or secondary cancer).

Staging helps doctors to create an individualised treatment plan for the patient. Other issues, such as their general health or the genetic characteristics of the tumour, can guide clinicians advising on the best course of action. 

Source: The Roy Castle Lung Cancer Foundation

Tags: Lung cancer