Gastric cancer staging

	    Primary tumor
           TX                      Cannot be assessed
           T0                      No evidence of primary tumor
           Tis                     Carcinoma-in-situ
           T1                      Tumor invades the lamina propria or submucosa
           T2                      Tumor invades muscularis propria or subserosa
           T2a                     Tumor invades musculris propria
           T2b                     Tumor invades the subserosa
           T3                      Tumor penetrates serosa without invasion of adjacent structures
           T4                      Tumor invades adjacent structures       
           Lymph node involvement (N)
           NX                     Cannot be assessed
           N0                      No regional lymph nodes metastases
           N1                      Metastases to 1-6 regional lymph nodes
           N2                      Metastases in 7-15 regional lymph nodes 
           N3                      Metastases to greater than 15 lymph nodes 
           Distant metastases (M)
           MX                     Distant metastases cannot be assessed
           M0                      No distant metastases 
           M1                      Distant metastases 
           Staging group
           Stage 0               Tis, NOM0
           Stage IA              T1,N0.M0
           Stage IB              T1,N1,M0
           Stage II              T1,N2.M0
           Stage IIIA            T2a/b,N2,M0
           Stage IIIB            T3,N2,M0
           Stage IV              T4,N1-3,M0
                                 T1-3,N3,M0
                                 Any T, any  N, M1