e 0-3 with o meaning no positive lymph nodes and 3 many positive lymph nodes
M is either 0 or 1 with 0 meaning no spread and 1 meaning that there is spread
The number systems assigns numbers from 1-4 (or often the letters A-D) to describe the cancer. One is commonly used to signify small tumors with no spread and no positive lymph nodes, while four would mean that there is spread and positive lymph nodes.
Esophageal cancer is similar to other forms of cancer in that it spreads through three different processes. The cancer at the site of its origination is known as the primary cancer. If a cancer spreads or starts to grow somewhere else it is known as the secondary cancer, commonly referred to as metastasis. Cancer cells are not as tightly unified as regular cells and as cancerous cells break off from the tumor they are able to spread to other areas of the body through three modalities. The first is known as local spread where in the cancer starts
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