Alternate-day treatment with S-1 in patients with gastric cancer: a retrospective study of strategies for reducing toxicity

Int J Clin Oncol. 2010 Apr;15(2):166-71. doi: 10.1007/s10147-010-0036-y. Epub 2010 Mar 2.


Background: In patients with adverse events of S-1, the dose is generally reduced or the treatment cycle is shortened. Whether the therapeutic effectiveness of modified regimens is similar to that of the standard dosage remains unclear.

Methods: We retrospectively studied patients with gastric cancer who received S-1 on alternate days.

Results: A total of 266 patients received S-1 on alternate days. In 116 patients, S-1 was initially given at the standard dosage but was switched to alternate-day treatment because of toxicity within 28 days on average. The other 150 patients initially received alternate-day treatment because of poor general condition. In the adjuvant chemotherapy group (n = 96), the 3-year survival rate was 88% in patients with stage II, 73% in stage IIIA, and 67% in stage IIIB who underwent D2 lymph-node dissection. In the palliative surgery group (n = 96), the response rate was 13%, with a median survival time (MST) of 624 days. In patients with unresectable/recurrent disease (n = 74), the response rate was 25%, with an MST of 338 days. Among the 116 patients who initially received treatment on consecutive days, 100% had grade 1, 53% had grade 2, and 5.2% had grade 3 adverse events. When S-1 was switched to alternate-day treatment, toxicity decreased in all patients. In the 266 patients who received alternate-day treatment, 8% had grade 1, 6% had grade 2, and 0% had grade 3 adverse events.

Conclusion: Alternate-day treatment with S-1 may have milder adverse events without compromising therapeutic effectiveness.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Antimetabolites, Antineoplastic / administration & dosage*
  • Antimetabolites, Antineoplastic / adverse effects
  • Chemotherapy, Adjuvant
  • Disease-Free Survival
  • Drug Administration Schedule
  • Drug Combinations
  • Female
  • Gastrectomy
  • Humans
  • Kaplan-Meier Estimate
  • Lymph Node Excision
  • Male
  • Middle Aged
  • Oxonic Acid / administration & dosage*
  • Oxonic Acid / adverse effects
  • Palliative Care
  • Retrospective Studies
  • Stomach Neoplasms / drug therapy*
  • Stomach Neoplasms / mortality
  • Stomach Neoplasms / surgery
  • Tegafur / administration & dosage*
  • Tegafur / adverse effects
  • Time Factors
  • Treatment Outcome


  • Antimetabolites, Antineoplastic
  • Drug Combinations
  • S 1 (combination)
  • Tegafur
  • Oxonic Acid