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.
Outer to the lamina propria is this layer called muscularis mucosa.
Outer to which, lies this layer which is called as submucosa. Then lies muscularis propria.
And on the outermost aspect, lies this layer which is called as serosa or adventitia.
Now, let’s discuss the T-staging for esophageal cancer.
First is This, or carcinoma in situ. This is not considered malignant and is localized to the epithelium.
Infiltration of lamina propria or muscularis mucosa is called as T1a disease.
Infiltration into submucosa is called as T1b. Muscularis propria infiltration is called as T2. And infiltration of serosa or adventitia is called as T3.
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.
And here, it has infiltrated into the lungs or pleura. And here it infiltrates the diaphragm. It may also infiltrate anteriorly, into the trachea. Or into the great vessels of the heart.
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.
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. And here it has spread to the liver in form of multiple nodular deposits.
Rarely, cancer may spread to bones.
So this completes the TNM for esophageal cancer staging.
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