Regression of prostate cancer following administration of Genistein Combined Polysaccharide (GCP), a nutritional supplement: a case report

J Altern Complement Med. 2002 Aug;8(4):493-7. doi: 10.1089/107555302760253694.


Purpose: It has been reported that genistein, an isoflavone used in soybeans, has antiprostate cancer effects. Genistein Combined Polysaccharide (GCP trade mark; AMino Up, Sapporo, Japan), a nutritional supplement manufactured in Japan, is composed of genistein and a polysaccharide obtained from basidiomycetes (mycelia) that grows in a variety of mushrooms.

Methods: We report a case of a patient with a biopsy proven prostate cancer showing clinical and pathologic evidence of regression following administration of GCP. The patient was enrolled in an Institutional Review Board (IRB)-approved protocol and received GCP for 6 weeks prior to radical prostatectomy.

Results: The patient's prostate-specific antigen (PSA) decreased from an initial value of 19.7 to 4.2 ng/mL after 44 days of low-dose GCP. No cancer was identified in the radical prostatectomy specimen and no side effects were observed in this patient.

Conclusion: This case suggests that GCP, which has shown potent inhibitory effects against prostate cancer in vitro, may have some potential activity in the treatment and prevention of prostate cancer.

Publication types

  • Case Reports

MeSH terms

  • Antineoplastic Agents / pharmacology
  • Antineoplastic Agents / therapeutic use*
  • Basidiomycota*
  • Biomarkers, Tumor / blood
  • Dose-Response Relationship, Drug
  • Genistein / pharmacology
  • Genistein / therapeutic use*
  • Humans
  • Lentinula
  • Male
  • Middle Aged
  • Mycelium
  • Polysaccharides / therapeutic use*
  • Prostate-Specific Antigen / blood
  • Prostatic Neoplasms / drug therapy*
  • Prostatic Neoplasms / immunology
  • Prostatic Neoplasms / pathology*
  • Reishi
  • Remission Induction
  • Treatment Outcome


  • Antineoplastic Agents
  • Biomarkers, Tumor
  • Polysaccharides
  • Genistein
  • Prostate-Specific Antigen