title: Stage-specific effect of adjuvant therapy following gastric cancer resection: a population-based analysis of 4,041 patients.
abstract: BACKGROUND
  Adjuvant chemoradiotherapy improved survival in patients with resected gastric adenocarcinoma in the Southwest Oncology Group/Intergroup 0116 trial. Our objective was to examine the impact of adjuvant treatment on overall survival (OS) in the general population.
  
  
  METHODS
  Patients 18-85 years old who had undergone resection of non-metastatic gastric adenocarcinoma between May 2000 and December 2003, were identified from the Surveillance Epidemiology and End Results (SEER) database. Patients who had received pre-operative irradiation, had unknown stage or radiation status, or had a survival of 3 months or less from the date of diagnosis were excluded. Survival of those who received post-operative irradiation was compared with those who did not; Kaplan-Meier methods and Cox proportional hazards models were used.
  
  
  RESULTS
  Of 4,041 patients, there was improved survival for those receiving adjuvant irradiation for stages III and IVM0, with a median OS of 31 versus 24 months (P = 0.005) and 20 versus 15 months (P < 0.001), respectively, and a trend for improved survival in univariate analysis of stage II (P = 0.0535). In final adjusted analysis, adjuvant irradiation significantly improved OS in stages III (HR: 0.71, P = 0.0007) and IVM0 (HR: 0.66, P < 0.0001). Adjusted analysis using a propensity score suggested that the benefit of adjuvant irradiation was similar in stage-II and -III patients. However, there was no statistical improvement in survival for stage-Ib and -II patients who had received adjuvant irradiation.
  
  
  CONCLUSIONS
  In this population-based analysis, adjuvant radiotherapy for stage-III and IVM0 gastric cancer significantly improved OS. Analysis of stage-Ib and -II patients is limited by small numbers, but there may not be the same benefit.
authors.affiliation: Department of Surgery, University of Toronto, Toronto, Ontario, Canada. natalie.coburn@sunnybrook.ca
authors.forename: Natalie G
authors.initials: NG
authors.lastname: Coburn
authors.forename: Anand
authors.initials: A
authors.lastname: Govindarajan
authors.forename: Calvin H L
authors.initials: CH
authors.lastname: Law
authors.forename: Ulrich
authors.initials: U
authors.lastname: Guller
authors.forename: Alex
authors.initials: A
authors.lastname: Kiss
authors.forename: Jolie
authors.initials: J
authors.lastname: Ringash
authors.forename: Carol J
authors.initials: CJ
authors.lastname: Swallow
authors.forename: Nancy N
authors.initials: NN
authors.lastname: Baxter
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D016016:Proportional Hazards Models; D018714:Radiotherapy, Adjuvant; D018426:SEER Program; D013274:Stomach Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery*; D016019:Survival Analysis