When diagnosed with any condition, especially cancer, the doctor runs some tests to understand at which stage the condition is at. The stage of cancer conveys a lot of important information, like how far cancer has spread, which parts of the body have been affected, and how far along cancer has progressed. Various diagnostic tests are used to determine the stages of cancer.

Putting the findings of different diagnostic tests into different buckets is what helps the surgeons determine a particular stage of cancer. To make this classification, a system is used. This is known as the TNM staging system.

This staging system answers the following questions:

Tumor (T)
What is the size of the primary tumor? What is the location of the primary tumor?

After these questions are answered, this stage is further divided into various substages as follows:

• TX: The tumor is still not at a stage to be evaluated.
• T0: There is no evidence for the presence of a tumor.
• T1: The only region where a tumor is present is in the kidney. At its largest area, the tumor has a size of 7cm or less. If the tumor is 4cm or less at its largest area, then it is classified as T1a and if the tumor is between 4cm and 7cm at its largest area, then it is classified as T1b.
• T2: The only region where a tumor is present is in the kidney. At its largest area, the tumor has a size of 7cm or more. If the tumor is larger than 7cm but smaller than 10cm at its largest area, then it is classified as T2a. Similarly, if the tumor is larger than 10cm at its largest area, then it is classified as T2b.
• T3: At this stage, the tumor has spread to perinephric tissue and major veins around the kidney. The adrenal gland has not yet been affected. This stage is further divided into the substages T3a, T3b, and T3c based on which veins and tissues around the kidney have been affected.

Node (N)
This stands for the lymph nodes. Lymph nodes near the kidneys would be known as regional lymph nodes and lymph nodes in other organs would be known as distant lymph nodes. This is further divided into the following stages:

• NX: The regional lymph nodes are not still in a stage where they can be evaluated.
• N0 (N plus zero): The regional lymph nodes have still not been affected by cancer at this stage.
• N1: The tumor has spread to various other parts of the body beyond the kidney.

Metastasis (M)
This describes if cancer has spread to other parts of the body. This is known as distant metastasis. The different substages involved are as follows:

• M0: The tumor has not yet metastasized.
• M1: The tumor has moved beyond the kidney and spread to other parts of the body.