Kidney Cancer TNM Staging Explained

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kidney-cancer

Once the kidney cancer has been diagnosed through various investigations, TNM staging helps to determine the disease prognosis and to select an appropriate treatment strategy

Before discussing the staging for kidney cancer, let’s have a look at the anatomy of kidney that will help us to understand staging in a better way.

Normal Anatomy of Kidney explained with Video and Images

Video Transcript:

They are a pair of organs located in the back of the abdomen, each of which is 4 to 5 inches long. Their main function is to filter the blood and remove waste from the body and regulate the balance of fluids and electrolytes.

Diagram of Kidney

This tube like structure, called ureter carries the urine produced after filtering the blood.

ureter diagram

This funnel like structure called renal pelvis is formed by dilated proximal part of the ureter in kidney.

renal pelvis

It is formed by convergence of 2-3 major calyces.

major calyx

These structures called as renal pyramids, consist of tubules that transport urine from cortical or outer part of kidney to the calyces and then to the pelvis and ureter.

renal pyramid diagram

This structure called as Adrenal Gland or suprarenal gland is present above the kidney, which produces a number of steroid hormones.

adrenal gland

Perirenal fat is the accumulation of fatty tissue that completely surrounds the kidney and is enclosed by a layer called as Renal Fascia. Another name for which is Gerota’s Fascia.

Gerota’s Fascia diagram

Renal veins are the veins that carry the blood filtered by kidney and ultimately drain into the Inferior Vena Cava.

Inferior Vena Cava

Renal arteries are the branches of aorta that carry blood from heart to the kidneys for filtration.

renal arteries

Kidney Cancer TNM Staging explained with Video and Images

Video Transcript:

Now let us discuss the kidney cancer T staging.

It is called as T1 when the tumor is 7 cm or less in the greatest dimension and is limited to the kidney.

T1, tumor is 7 cm or less

It is called as T2 when the tumor is greater than 7 cm in the greatest dimension and is limited to the kidney.

T2, tumor is more than 7 cm

T3 includes cases in which the tumor extends to renal vein and its segmental branches, or renal sinus fat.

T3, tumor extends to renal vein or renal sinus fat

T3 also includes cases in which the tumor extends into the perirenal fat, but not beyond Gerota’s Fascia, as you can see in this figure.

T3, tumor extends into the perirenal fat

Extension of the tumor into inferior vena cava is also T3.

T3, extends to inferior vena cava

And when the tumor extends beyond the Gerota’s Fascia, as you can see in the figure, it is called as T4.

T4, extends beyond Gerota’s fascia

Infiltration of the adrenal gland is also T4.

T4, ipsilateral adrenal gland involvement

 

The infographic below summarizes the T Staging of Kidney Cancer

T staging

Now, lets come to the N-staging or nodal staging of kidney cancer. Involvement of regional lymph nodes of the kidney, as you can see in this figure, is called as N1.

N staging - extends to regional nodes

And lastly, we come to the M-staging or the metastatic staging of kidney cancer. This figure shows multiple metastatic deposits in the liver.

metastasis to liver

And here cancer has spread to the lungs in form of multiple nodular deposits.

metastasis to lungs

It may also spread to the peritoneum in the form of peritoneal deposits, as you can see in this figure.

metastasis to peritoneum

Metastatic deposits in the adrenal gland without direct extension of a tumor may also be seen.

Metastatic deposits in the adrenal gland

Sometimes, it may also spread to the brain or bones.

N and M Staging

So with this, we come to the end of TNM staging for renal cancer.

TNM Staging of Kidney Cancer

“T” stands for “Tumor Size”, “N” for “Lymph Nodes”, and “M” for “Metastasis”. Numbers and/or letters after T (1, 2, 3, and 4), N (0 and 1), and M (0 and 1) provide more details about each of these factors. Once T, N, and M categories are determined, this information is combined to assign an overall stage (from I to IV).

T Staging

T1 – Tumor is limited to kidney and measures </=7 cm in largest dimension. 

T2 – Tumor is limited to kidney and measures >7 cm in largest dimension.

T3 – Tumor has extended up to a renal vein (or its branches) or has spread to inferior vena cava; or the fatty tissue around the kidney, but not to the adrenal gland or beyond Gerota’s fascia.

T4 – The tumor has extended beyond the Gerota’s fascia and may be up to the adrenal gland. 

N Staging

N0 – No spread of disease to nearby lymph nodes or distant body organs.

N1 – Cancer has spread to regional lymph nodes 

M Staging

M0 – Cancer has not spread to distant body organs.

M1 – Cancer has spread to distant body organs like the brain, bones, lungs, liver, peritoneum, etc.

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