Esophageal Cancer TNM Staging Explained In Detail

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esophageal-cancer

Once the esophageal 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, let’s have a look at the normal anatomy of esophagus that will help to understand the staging better.

Normal Anatomy of Esophagus explained with Video and Images

Video Transcript:

In the chest cavity, this trachea lies in front which helps us breathing.

trachea

As you can see, behind the trachea lies the esophagus.

esophagus

Heart also lies in the chest cavity in front of esophagus.

heart diagram

And on both sides, lie the lungs.

lungs

And as you can see in the figure, esophagus crosses the diaphragm to enter into the abdomen, where it joins the stomach.

stomach diagram

Esophagus starts at a distance of 15 cm from upper incisors, at the level of cricopharyngeus muscle.

cricopharyngeus muscle

And the lowest most end of the esophagus is at distance of 40 cm from upper incisors, at the level of gastroesophageal junction.

gastroesophageal junction

So the total length of the esophagus is 25 cm. The upper 3 cm of esophagus is called as cervical esophagus.

cervical esophagus

And below that esophagus maybe divided into 3 parts – upper, middle and lower esophagus, as you can see in the figure.

upper, middle and lower esophagus

Carcinoma rising from the upper and middle esophagus is mostly squamous cell carcinoma. Adenocarcinoma is seen very rarely in this region.

Whereas, in the lower 1/3d of the esophagus, it is mostly adenocarcinoma, although squamous cell carcinoma may also be seen.

So after knowing the anatomy of esophagus, now let’s discuss the staging for esophageal cancer.

TNM Staging Of Esophageal Cancer explained with Video and Images

Video Transcript:

The staging system used for esophageal cancer is known as TNM staging system.

This diagram is a magnified image of a cross-section of the wall of esophageal. Imagine the upper part is the inner side and the lower part is the outer side. The innermost layer is called as epithelium, followed by this layer, called as lamina propria.

epithelium and lamina propria

Outer to the lamina propria is this layer called muscularis mucosa.

muscularis mucosa

Outer to which, lies this layer which is called as submucosa. Then lies muscularis propria.

submucosa and muscularis propria

And on the outermost aspect, lies this layer which is called as serosa or adventitia.

serosa or adventitia

Now, let’s discuss the T-staging for esophageal cancer.

First is Tis, or carcinoma in situ. This is not considered malignant and is localized to the epithelium.

Tis, or carcinoma in situ

Infiltration of lamina propria or muscularis mucosa is called as T1a disease.

T1a - Infiltration of lamina propria or muscularis mucosa

Infiltration into submucosa is called as T1b.

T1b - Infiltration into submucosa

Muscularis propria infiltration is called as T2. And infiltration of serosa or adventitia is called as T3.

T2 is muscularis propria inv, T3 is serosa inv.

Till T3 disease, the cancer is limited to the wall of esophageal and does not extend outside to involve adjacent structures.

Whereas in T4 disease, cancer infiltrates through the wall of esophageal and involves adjacent structures, like in this figure, cancer has infiltrated into the heart or pericardium.

T4 stage - infiltrated into the heart or pericardium

And here, it has infiltrated into the lungs or pleura.

T4 stage - infiltrated into the lungs or pleura.

And here it infiltrates the diaphragm.

T4 - infiltrates the diaphragm

It may also infiltrate anteriorly, into the trachea. Or into the great vessels of the heart.

Esophageal Cancer T Staging

So this finishes the T-stage, now let’s come to the N-stage.

N staging maybe N1, N2 or N3, depending upon the number of lymph nodes involved.

involving regional lymph nodes

Last comes the M or the metastatic staging, which determines the spread of cancer to distant sites. Like in this figure, cancer has spread to involve both the lungs.

metastasis to lungs

And here it has spread to the liver in form of multiple nodular deposits.

metastasis to liver

Rarely, cancer may spread to bones.

esophageal-cancer-N-and-M-staging

So this completes the TNM staging for esophageal cancer.

Esophagus Cancer TNM Staging

Esophageal 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 esophageal 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.

T STAGING DESCRIPTION
Tis Pre-cancerous or cancerous cells present only in the epithelium of esophagus
T1a Tumor invades mucosa
T1b Cancerous cells present in all layers of the esophagus epithelium and into the middle muscular layer
T2 Tumor invades the muscular layer (muscularis propria)
T3 Tumor invades in the serosa/adventitia
T4a Tumor invades the pleura, pericardium, azygous vein, diaphragm , or peritoneum
T4b Tumor invades other adjacent structures, such as aorta, vertebral body, or airway.

Esophageal Cancer T Staging

N STAGING DESCRIPTION
N0 No regional lymph node involvement
N1 Tumor has spread to 1 to 2 regional lymph nodes
N2 Tumor has spread to 3 to 6 regional lymph nodes
N3 Tumor has spread to 7 or more regional lymph nodes

M STAGING DESCRIPTION
M0 No spread to distant sites
M1 Spread to distant sites like lungs, pleura, peritoneum, liver, bones, etc


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