The "T" stage is as follows:
• Tis-"in-situ cancer"-very superficial tumor, without invasion of the stomach wall
• T1-tumor invades into only the superficial portions of the stomach wall
• T2-tumor invades into the deeper layers of the stomach wall
• T3-tumor extends through the stomach wall into the fat outside of the stomach
• T4-tumor extends outside the stomach wall and invades into other organs
The "N" stage is as follows:
• N0-no spread to lymph nodes
• N1-tumor spread to 1-6 lymph nodes
• N2-tumor spread to 7-15 lymph nodes
• N3-tumor spread to more than 15 lymph nodes
The "M" stage is as follows:
• M0-no tumor spread to other organs
• M1-tumor spread to other organs
The overall stage is based on a combination of these T, N, and M parameters:
• Stage IA-T1N0M0
• Stage IB-T1N1M0 or T2N0M0
• Stage II-T1N2M0 or T2N1M0 or T3N0M0
• Stage IIIA-T2N2M0 or T3N1M0 or T4N0M0
• Stage IIIB-T3N2M0 or T4N1M0
• Stage IV-T4N2M0 or T1-3N3M0 or T4N2-3M0 or any M1
The Modified Astler-Coller (MAC) system is simpler (thankfully), but can be corresponded to the TNM system:
MAC system TNM stage Characteristics
A TisN0M0 lymph nodes not involved; tumor very superficial in stomach
B1 T1-2N0M0 lymph nodes not involved; tumor deeper, but still within stomach wall (not entire way through)
B2 T3N0M0 lymph nodes not involved; tumor through the stomach wall
B3 T4N0M0 lymph odes not involved; tumor invading into other organs
C1 Tis-2N1-3M0 lymph nodes involved, but tumor not through the stomach wall
C2 T3N1-3M0 lymph nodes involved and tumor through the stomach wall
C3 T4N1-3M0 lymph nodes involved and tumorinvading into other organs
