Tumor size

Hi Bryn,

The TNM system describes 3 key pieces of information:

• T indicates the size of the main (primary) tumor and whether it has grown into nearby areas.
• N describes the extent of spread to nearby (regional) lymph nodes. Lymph nodes are small bean-sized collections of immune system cells to which cancers often spread first.
• M indicates whether the cancer has spread (metastasized) to other parts of the body. (The most common sites of spread are to the lungs, bones, liver, brain, and distant lymph nodes.)

Numbers or letters appear after T, N, and M to provide more details about each of these factors. The numbers 0 through 4 indicate increasing severity. The letter X means “cannot be assessed because the information is not available.”

T categories for kidney cancer

TX: The primary tumor cannot be assessed (information not available).

T0: No evidence of a primary tumor.

T1: The tumor is only in the kidney and is no larger than 7 centimeters (cm), or a little less than 3 inches, across

• T1a: The tumor is 4 cm (about 1½ inches) across or smaller and is only in the kidney.
• T1b: The tumor is larger than 4 cm but not larger than 7 cm across and is only in the kidney.

T2: The tumor is larger than 7 cm across but is still only in the kidney.

• T2a: The tumor is more than 7 cm but not more than 10 cm (about 4 inches) across and is only in the kidney
• T2b: The tumor is more than 10 cm across and is only in the kidney

T3: The tumor is growing into a major vein or into tissue around the kidney, but it is not growing into the adrenal gland (on top of the kidney) or beyond Gerota’s fascia (the fibrous layer that surrounds the kidney and nearby fatty tissue).

• T3a: The tumor is growing into the main vein leading out of the kidney (renal vein) or into fatty tissue around the kidney
• T3b: The tumor is growing into the part of the large vein leading into the heart (vena cava) that is within the abdomen.
• T3c: The tumor has grown into the part of the vena cava that is within the chest or it is growing into the wall of the vena cava.

T4: The tumor has spread beyond Gerota’s fascia (the fibrous layer that surrounds the kidney and nearby fatty tissue). The tumor may have grown into the adrenal gland (on top of the kidney).

N categories for kidney cancer

NX: Regional (nearby) lymph nodes cannot be assessed (information not available).

N0: No spread to nearby lymph nodes.

N1: Tumor has spread to nearby lymph nodes.

M categories for kidney cancer

M0: There is no spread to distant lymph nodes or other organs.

M1: Distant metastasis is present; includes spread to distant lymph nodes and/or to other organs. Kidney cancer most often spreads to the lungs, bones, liver, or brain.

Stage grouping

Once the T, N, and M categories have been assigned, this information is combined to assign an overall stage of I, II, III, or IV. The stages identify cancers that have a similar prognosis (outlook) and thus are treated in a similar way. Patients with lower stage numbers tend to have a better prognosis.