title: Postoperative adjuvant chemotherapy with S-1 alters recurrence patterns and prognostic factors among patients with stage II/III gastric cancer: A propensity score matching analysis.
abstract: BACKGROUND
  A phase 3 evidence indicates that S-1 adjuvant is beneficial among East Asian patients with stage II/III gastric cancer (GC). However, little is known about the changes in prognostic factors and recurrence patterns after it has become widespread as a standard of care. The present study compared prognostic factors of patients with stage II/III GC treated with or without S-1 adjuvant with formulate appropriate risk stratification strategies.
  
  
  METHODS
  We enrolled 171 patients with stage II/III GC, 92 patients who underwent gastrectomy alone, and 79 patients treated with S-1 adjuvant. To balance more strictly the essential variables including stage of progression, we conducted propensity score analysis and 70 pairs of patients were generated from each group. Prognostic factors were compared between the groups and initial recurrence patterns were investigated to explore reasons for the change.
  
  
  RESULTS
  In concordance with the previous phase 3 trial, overall and recurrence-free survival were better for the S-1 adjuvant group. In the surgery alone group, carcinoembryonic antigen ≥ 5 ng/mL, total gastrectomy, vessel invasion, pT4, and stage 3 were identified as significant prognostic factors. In striking contrast, macroscopic tumor size ≥ 50 mm was the only significant prognostic factor for the S-1 adjuvant group. The lower overall recurrence rate of the S-1 adjuvant group was attributable mainly to a significant decrease of peritoneal recurrence.
  
  
  CONCLUSIONS
  Prognostic factors changed substantially after implementation of S-1 adjuvant treatment. Macroscopic tumor size should be considered for patient stratification and selection of treatment options for patients with stage II/III GC.
authors.affiliation: Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Nagoya, Japan. Electronic address: m-kanda@med.nagoya-u.ac.jp.
authors.forename: Mitsuro
authors.initials: M
authors.lastname: Kanda
authors.affiliation: Center for Clinical Research, Aichi Medical University, Nagakute, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Murotani
authors.affiliation: Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kobayashi
authors.affiliation: Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Chie
authors.initials: C
authors.lastname: Tanaka
authors.affiliation: Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Suguru
authors.initials: S
authors.lastname: Yamada
authors.affiliation: Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Fujii
authors.affiliation: Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Goro
authors.initials: G
authors.lastname: Nakayama
authors.affiliation: Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sugimoto
authors.affiliation: Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Koike
authors.affiliation: Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Michitaka
authors.initials: M
authors.lastname: Fujiwara
authors.affiliation: Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kodera
mesh_terms: D000368:Aged; D000964:Antimetabolites, Antineoplastic / Q000627:therapeutic use*; D017024:Chemotherapy, Adjuvant / Q000379:methods*; D003131:Combined Modality Therapy; D004338:Drug Combinations; D005260:Female; D005743:Gastrectomy; D006801:Humans; D008297:Male; D016555:Matched-Pair Analysis; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology / Q000517:prevention & control; D009367:Neoplasm Staging; D010094:Oxonic Acid / Q000627:therapeutic use*; D011182:Postoperative Care; D011379:Prognosis; D057216:Propensity Score; D012189:Retrospective Studies; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000601:surgery*; D015996:Survival Rate; D005641:Tegafur / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D000964:Antimetabolites, Antineoplastic; D004338:Drug Combinations; C079198:S 1 (combination); D005641:Tegafur; D010094:Oxonic Acid