Effects of commercially available soy products on PSA in androgen-deprivation-naïve and castration-resistant prostate cancer.
OBJECTIVE
No standard therapeutic option exists for men with prostate cancer who have failed local therapy, have no gross metastatic disease, and whose only manifestation of disease is a rising prostate-specific antigen (PSA) level. Soy products are able to affect PSA kinetics in some men with prostate cancer, and this effect has been attributed to the decreased expression of the androgen receptor and other mechanisms.


METHODS
We treated 10 men with rising PSA levels after radical prostatectomy and salvage radiotherapy with commercially available soy products. Scans revealed no gross metastatic disease. Three men also had been receiving androgen-deprivation therapy (ADT) and had rising PSA levels that were consistent with castration-resistant (CR) disease. We reported the results of this modality on PSA levels, PSA kinetics, and the duration of PSA response.


RESULTS
Responses occurred in 4 of 7 (57%) patients with ADT-naïve disease and 1 of 3 (33%) patients with CR disease. The median duration of treatment response was 24 months. The overall clinical benefit, therefore, was noted in 5 of 10 (50%) patients. Therapy was well tolerated.


CONCLUSIONS
Our findings are fairly congruent with what has been described in the literature on the use of this modality in prostate cancer. We used commercially available soy products. We also show that soy can provide benefit in CR prostate cancer. Our clinical experience suggests that soy supplementation using commercially available soy products can have durable beneficial effects on PSA levels and PSA kinetics in some men with prostate cancer.
Division of Hematology/Oncology, Penn State Hershey Cancer Institute, Penn State Milton S. Hershey Medical Center, Hershey, PA 17033-0850, USA. mjoshi@psu.hmc.edu
Monika
M
Joshi
Nicole M
NM
Agostino
Rebecca
R
Gingrich
Joseph J
JJ
Drabick
D000368:Aged; D000369:Aged, 80 and over; D000726:Androgen Antagonists / Q000627:therapeutic use; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000378:metabolism*; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000178:diet therapy* / Q000378:metabolism / Q000628:therapy; D012189:Retrospective Studies; D016879:Salvage Therapy; D045730:Soy Foods; D041942:Soy Milk; D016896:Treatment Outcome
D000726:Androgen Antagonists; D018931:Antineoplastic Agents, Hormonal; D017430:Prostate-Specific Antigen