The "T" stage is as follows:
Tis-carcinoma in situ
T1-tumor confined to the inner layer of the esophageal wall (submucosa or lamina propria)
T2-tumor invades into the muscular layer of the wal
l
T3-tumor invades into the outer layer of the wall (adventitia)
T4-tumor invades into other structures or organs
The "N" stage is as follows for any subsite:
N0-no spread to lymph nodes
N1-tumor spread to regional lymph nodes
-lymph nodes outside the chest are considered "M1"
The "M" stage is as follows:
M0-no tumor spread to other organs
M1-tumor spread to other organs
This is also broken down by site of the primary tumor within the esophagus:
Tumors of the lower esophagus:
M1a-cancer spread to the lymph nodes in the abdomen (called celiac nodes).
M1b-cancer has spread to other parts of the body.
Tumors of the upper esophagus:
M1a-cancer spread to the lymph nodes in the neck (called cervical or supraclavicular nodes).
M1b-cancer has spread to other parts of the body.
The overall stage is based on a combination of these T, N, and M parameters:
Stage 0: Cancer in situ.
Stage I: Cancer in the two inside layers of the esophagus (T1N0M0)
Stage IIA: Cancer in any of the four layers of the esophagus (T2-3N0M0)
Stage IIB: Cancer in any layer of the esophagus, with spread to lymph nodes near the
tumor (T1-2N1M0)
Stage III: Cancer is in the outside layer of the esophagus, or through the wall. Cancer is
also in the lymph nodes (T3-4N1M0)
Stage IVA: Cancer spread to the lymph nodes of the abdomen or neck (T1-4N0-1M1a)
Stage IVB: Cancer has spread to other parts of the body (T1-4N0-1M1b)
