title: A proposed staging system for primary gastric lymphoma.
abstract: BACKGROUND
  Although primary gastric lymphoma is the most common extranodal lymphoma, no specific staging system exists.
  
  
  METHODS
  The authors reviewed 98 cases histologically classified according to the Working Formulation, including low grade B-cell lymphoma of mucosa-associated lymphoid tissue type. Survival rates were calculated by the Kaplan-Meier method according to T, N, and M of the general rules of the International Union Against Cancer TNM system. The definitions of these categories are as follows: T1, tumor invades the lamina propria or submucosa; T2, the muscularis propria; T3, the subserosa; T4, the serosa without invasion of adjacent structures; T5, adjacent structures; N0, no regional lymph node metastasis; N1, perigastric lymph nodes within 3 cm of the edge of the primary tumor; N2, perigastric lymph nodes more than 3 cm from the edge of the primary tumor or in lymph nodes along the left gastric, common hepatic, splenic, or celiac arteries; N3, paraaortic and hepatoduodenal lymph nodes and/or other intraabdominal lymph nodes; N4, beyond N3; M0, no distant metastasis; and M1, positive.
  
  
  RESULTS
  The overall 5-year survival rate was 83.5%; it was 100% in T1, 82.4% in T2, 84.2% in T3, 52.9% in T4, and 33.3% in T5; 93.9% in N0, 90.5% in N1, 66.2% in N2, and 44.4% in N3/N4; and 86.0% in M0 and 25.0% in M1. Based on these results, the authors proposed a new staging system as follows: Stage I, T1/N0, N1/M0; Stage II, T1/N2/M0, T2,T3/N0,N1,N2/M0; Stage III, T4,T5/any N/M0, any T/N3, N4/M0; and Stage IV, any T/any N/M1. According to this system, the 5-year survival rate significantly decreased as the stage progressed: 100% in Stage I, 88.9% in Stage II, 52.1% in Stage III, and 25.0% in Stage IV. In Stages I and II, survival rates were not significantly different whether chemotherapy was done or not, whereas in Stage III all patients treated with surgery alone died.
  
  
  CONCLUSIONS
  This staging system is useful for assessing prognosis of and deciding a therapeutic plan for primary gastric lymphoma.
authors.affiliation: Second Department of Internal Medicine, Nagoya University School of Medicine, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Shimodaira
authors.forename: Y
authors.initials: Y
authors.lastname: Tsukamoto
authors.forename: Y
authors.initials: Y
authors.lastname: Niwa
authors.forename: H
authors.initials: H
authors.lastname: Goto
authors.forename: S
authors.initials: S
authors.lastname: Hase
authors.forename: T
authors.initials: T
authors.lastname: Hayakawa
authors.forename: T
authors.initials: T
authors.lastname: Nagasaka
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology; D008207:Lymphatic Metastasis / Q000473:pathology; D008223:Lymphoma / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods*; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D015996:Survival Rate