Stomach cancer TNM staging helps to determine the disease prognosis, and to select an appropriate treatment strategy. It is the most commonly used staging system for stomach or gastric cancer.
“T” stands for “Tumor Size”, “N” for “Lymph Nodes”, and “M” for “Metastasis”. Numbers and/or letters after T (is, 1a, 1b, 2, and 3), N (0, 1, 2, and 3), and M (0 and 1) provide more details about each of these factors. Higher the number means higher the severity of the disease.
Once T, N, and M categories are determined, this information is combined to assign an overall stage (from 0 to IV).
Tis – Pre-cancerous or cancer cells present only in the epithelium of gastric mucosa
T1 – Tumor invades mucosa or submucosa.
T2 – Tumor invades the muscular layer (muscularis propria)
T3 – Tumor invades in the subserosal connective tissue layer
T4a – Tumor invades the outermost serosa layer without affecting any nearby lymph node
T4b – Tumor invades adjacent structure/organs without affecting any nearby lymph node
N1 – Tumor has spread to 1 or 2 nearby lymph nodes
N2 – Tumor has spread to 3 to 6 nearby lymph nodes
N3a – Tumor has spread to 7 to 15 nearby lymph nodes
N3b – Tumor has spread to >/=16 nearby lymph nodes
M0 – Tumor has not spread to distant sites
M1 – Tumor has spread to non regional nodes or distant organs such as lungs, bones, brain, etc
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Before discussing the staging, we will understand the NORMAL ANATOMY OF STOMACH.
The stomach anatomy starts from the gastroesophageal junction and the most proximal part of the stomach is called as cardia.
After which comes the body and distally lies the antrum and pylorus.
Imagine this to be a cross-section from the stomach wall, and the upper part being the inside of the stomach and the lower part being the outside of the stomach.
On the innermost aspect lies the epithelium, outside to which lies the lamina propria.
Muscularis mucosa is the layer which lies outside the lamina propria.
Then comes the submucosa. Muscularis propria is the layer which lies outside the submucosa. Outside to which lie the subserosa.
And the outermost aspect lies this layer called as serosa.
Stomach Cancer TNM Staging:
|0||Tis N0 M0|
|IA||T1 N0 M0|
|IB||T2 N0 M0|
|T1 N1 M0|
|T2 N1 M0|
|T1 N2 M0|
|IIB||T3 N1 M0|
|T2 N2 M0|
|T1 N3a M0|
|T4a N0 M0|
|IIIA||T4b N0 M0|
|T4a N1/2 M0|
|T3 N2 M0|
|T2 N3a M0|
|IIIB||T4b N1-2 M0|
|T3-4a N3a M0|
|T1-2 N3b M0|
|IIIC||T4b N3a-3b M0|
|T3-4a N3b M0|
|IV||Any T Any N M1|
Watch the video below where Cancerbro explains the TNM STAGING OF STOMACH CANCER.
Now, after discussing the different layers of the stomach wall, let’s discuss the T-staging of the stomach cancer.
First is the Tis or carcinoma in situ. This is not considered as malignant and is localized to the epithelium.
Infiltration of lamina propria or muscularis mucosa is called as T1a disease.
Infiltration into the submucosa is called as T1b. Muscularis propria infiltration is called as T2.
Infiltration of subserosa is called as T3. And infiltration of the tumor into the serosa is called as T4a disease.
When the tumor extends through the stomach walls to involve the adjacent structures it is called as T4b.
In this figure, the tumor extends to involve the colon.
And here it infiltrates the pancreas.
And here the tumor infiltrates into the spleen.
And here it invades the kidney.
It may also infiltrate into the liver or the diaphragm.
This finishes the stomach cancer staging T, now next comes the N staging or the nodal staging.
The regional nodes which drain the stomach are different in different part of the stomach.
These nodes drain the lesser curvature of the stomach.
And these drain the upper part of the greater curvature of the stomach.
And these the lower part.
These nodes drain the pyloric antrum.
All the nodes draining the different part of the stomach, ultimately drain into these nodes which are called the coeliac nodes.
M staging refers to the distance spread of the tumor to different parts of the body.
Distant metastasis may be seen to the liver.
The peritoneum in form of multiple peritoneal deposits.
To the lungs in form of multiple nodular deposits.
Rarely, it may spread to the left supraclavicular lymph node which presents as nodular deposits in the left side of the neck.
Or a nodular deposit in the periumbilical region called as sister Mary Joseph Nodule.
It may also present as pelvic deposits in the rectovesical pouch or pouch of Douglas.
Or as nodular deposits in one or both the ovaries, called as Krukenberg’s tumor.
Very rarely, it may also spread to brain or bones.
This finishes the TNM for stomach cancer staging.