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
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.
This tube like structure, called ureter carries the urine produced after filtering the blood.
This funnel like structure called renal pelvis is formed by dilated proximal part of the ureter in kidney.
It is formed by convergence of 2-3 major calyces.
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.
This structure called as Adrenal Gland or suprarenal gland is present above the kidney, which produces a number of steroid hormones.
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.
Renal veins are the veins that carry the blood filtered by kidney and ultimately drain into the Inferior Vena Cava.
Renal arteries are the branches of aorta that carry blood from heart to the kidneys for filtration.
Kidney Cancer TNM Staging explained with Video and Images
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.
It is called as T2 when the tumor is greater than 7 cm in the greatest dimension and is limited to the kidney.
T3 includes cases in which the tumor extends to renal vein and its segmental branches, 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.
Extension of the tumor into inferior vena cava is also T3.
And when the tumor extends beyond the Gerota’s Fascia, as you can see in the figure, it is called as T4.
Infiltration of the adrenal gland is also T4.
The infographic below summarizes the T Staging of Kidney Cancer
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.
And lastly, we come to the M-staging or the metastatic staging of kidney cancer. This figure shows multiple metastatic deposits in the liver.
And here cancer has spread to the lungs in form of multiple nodular deposits.
It may also spread to the peritoneum in the form of peritoneal deposits, as you can see in this figure.
Metastatic deposits in the adrenal gland without direct extension of a tumor may also be seen.
Sometimes, it may also spread to the brain or bones.
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).
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.
N0 – No spread of disease to nearby lymph nodes or distant body organs.
N1 – Cancer has spread to regional lymph nodes
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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