Delay in initiation of postoperative adjuvant chemotherapy with S-1 monotherapy and prognosis for gastric cancer patients: analysis of a multi-institutional dataset

  • Koki Nakanishi
  • Mitsuro KandaEmail author
  • Seiji Ito
  • Yoshinari Mochizuki
  • Hitoshi Teramoto
  • Kiyoshi Ishigure
  • Toshifumi Murai
  • Takahiro Asada
  • Akiharu Ishiyama
  • Hidenobu Matsushita
  • Chie Tanaka
  • Daisuke Kobayashi
  • Michitaka Fujiwara
  • Kenta Murotani
  • Yasuhiro Kodera
Original Article



This study aimed to evaluate whether the timing of initiating postoperative chemotherapy with S-1 monotherapy affects gastric cancer patients’ prognosis.


A multi-institution dataset identified patients with pStage II or III gastric cancer who received S-1 monotherapy for over 6 months after curative resection between 2010 and 2014. Patients were divided into three groups based on the timing of S-1 monotherapy initiation. Prognostic factors for relapse-free survival (RFS) were investigated.


We classified 401 patients into groups as follows: S-1 administered within 6 weeks (n = 247), between 6 and 8 weeks (n = 95), and after 8 weeks (n = 59). The RFS times were not significantly different in the within 6 weeks group and the between 6 and 8 weeks group, but the after 8 weeks group had a shorter RFS time compared with the other two groups (within 6 weeks group vs. after 8 weeks group; P = 0.0044). By disease stage, this trend was the same. The multivariable analysis showed that a larger tumor size (≥ 50 mm), pStage III, and the after 8 weeks group were independent prognostic factors for RFS (after 8 weeks group: hazard ratio, 2.05; P = 0.0069). The prevalence of hematogenous metastasis as the initial recurrence site increased by delayed initiation of S-1. A forest plot revealed that delayed administration after 8 weeks was associated with a greater risk of recurrence in most subgroups.


Postoperative chemotherapy with S-1 monotherapy for gastric cancer is recommended to begin within 8 weeks after surgery.


Gastric cancer Timing of initiation S-1 Prognosis Postoperative chemotherapy 



We thank Edanz Group ( for editing a draft of this manuscript.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no competing interests.

Ethical approval

All procedures performed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1964 and later versions.

Informed consent

Informed consent was obtained from all individual participants included in the study.

Supplementary material

10120_2019_961_MOESM1_ESM.tif (5.8 mb)
Supplemental Figure 1. Disease-specific survival for each group. a: All patients; b: Patients with stage II; c: Patients with stage III (TIFF 5910 kb)


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Copyright information

© The International Gastric Cancer Association and The Japanese Gastric Cancer Association 2019

Authors and Affiliations

  • Koki Nakanishi
    • 1
  • Mitsuro Kanda
    • 1
    Email author
  • Seiji Ito
    • 2
  • Yoshinari Mochizuki
    • 3
  • Hitoshi Teramoto
    • 4
  • Kiyoshi Ishigure
    • 5
  • Toshifumi Murai
    • 6
  • Takahiro Asada
    • 7
  • Akiharu Ishiyama
    • 8
  • Hidenobu Matsushita
    • 9
  • Chie Tanaka
    • 1
  • Daisuke Kobayashi
    • 1
  • Michitaka Fujiwara
    • 1
  • Kenta Murotani
    • 10
  • Yasuhiro Kodera
    • 1
  1. 1.Department of Gastroenterological Surgery (Surgery II)Nagoya University Graduate School of MedicineNagoyaJapan
  2. 2.Department of Gastroenterological SurgeryAichi Cancer CenterNagoyaJapan
  3. 3.Department of SurgeryKomaki Municipal HospitalKomakiJapan
  4. 4.Department of SurgeryYokkaichi Municipal HospitalYokkaichiJapan
  5. 5.Department of SurgeryKonan Kosei HospitalKonanJapan
  6. 6.Department of SurgeryIchinomiya Municipal HospitalIchinomiyaJapan
  7. 7.Department of SurgeryGifu Prefectural Tajimi HospitalTajimiJapan
  8. 8.Department of SurgeryOkazaki City HospitalOkazakiJapan
  9. 9.Department of SurgeryTosei General HospitalSetoJapan
  10. 10.Biostatistics Center, Graduate School of MedicineKurume UniversityKurumeJapan

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