Clinical efficacy of protein-bound polysaccharide K in patients with gastric cancer undergoing chemotherapy with an oral fluoropyrimidine (S-1)

Eur J Surg Oncol. 2015 Jun;41(6):795-800. doi: 10.1016/j.ejso.2015.02.012. Epub 2015 Apr 3.


Background: The aim of the present study was to evaluate the clinical significance of protein-bound polysaccharide K (PSK) in patients with primary gastric cancer who were being treated with an oral fluoropyrimidine (S-1).

Methods: Clinical reports of 190 gastric cancer patients treated with S-1 chemotherapy, with or without PSK, at Kochi Medical School between 2007 and 2012 were investigated retrospectively to analyze survival. The neutrophil:lymphocyte ratio (NLR) was also evaluated as indicator of the immunoenhancing effect of PSK.

Results: Overall survival was significantly longer in patients treated with S-1 + PSK than in those given S-1 alone (hazard ratio for death, 0.608; 95% confidence interval 0.375-0.985; P = 0.041). Furthermore, there was a tendency for changes in the NLR during chemotherapy to be lower in the S-1 + PSK group than in the S-1 group, but the difference did not reach statistical significance (P = 0.054). When patients were divided into groups based on preoperative NLR (i.e. <2.5 and ≥2.5), the mean (±SEM) NLR 1 month after the beginning of chemotherapy in the NLR ≥2.5 subgroup was significantly lower in patients treated with S-1 + PSK rather than S-1 alone (1.7 ± 0.7 vs. 3.3 ± 4.1, respectively; P = 0.043).

Conclusions: Immunochemotherapy using PSK improves the survival of patients with advanced gastric cancer. The NLR may be a useful biomarker for evaluating prognosis in these patients.

Keywords: Gastric cancer; Immunochemotherapy; Neutrophil to lymphocyte ratio; Oral fluorouracil anticancer drug; Protein-bound polysaccharide-K.

MeSH terms

  • Adenocarcinoma / blood
  • Adenocarcinoma / drug therapy*
  • Adenocarcinoma / surgery
  • Aged
  • Aged, 80 and over
  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use*
  • Drug Combinations
  • Female
  • Fungal Proteins / administration & dosage
  • Fungal Proteins / immunology
  • Humans
  • Immunotherapy
  • Kaplan-Meier Estimate
  • Lymphocyte Count
  • Lymphocytes*
  • Male
  • Middle Aged
  • Neutrophils*
  • Oxonic Acid / administration & dosage
  • Polysaccharides / administration & dosage
  • Polysaccharides / immunology
  • Retrospective Studies
  • Stomach Neoplasms / blood
  • Stomach Neoplasms / drug therapy*
  • Stomach Neoplasms / surgery
  • Survival Rate
  • Tegafur / administration & dosage


  • Drug Combinations
  • Fungal Proteins
  • Polysaccharides
  • protein-bound polysaccharide K, Basidiomycetes
  • S 1 (combination)
  • Tegafur
  • Oxonic Acid