Effects of Commercially Available Soy Products on PSA in Androgen-deprivation-naïve and Castration-resistant Prostate Cancer

Monika Joshi, MD; Nicole M. Agostino, MD; Rebecca Gingrich, MSN; Joseph J. Drabick, MD, FACP

Disclosures

South Med J. 2011;104(11):736-740. 

In This Article

Abstract and Introduction

Abstract

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.

Introduction

No standard therapeutic option exists for men with prostate cancer who have failed local therapy with radical prostatectomy (RP) and salvage radiotherapy (RT), have no gross metastatic disease, and whose only manifestation of disease is a rising prostate-specific antigen (PSA) level.[1] The therapeutic options for such patients include observation, androgen-deprivation therapy (ADT), or clinical trial.[1] The use of ADT in this scenario remains controversial because there is no proven survival benefit and treatment has potential morbidity, which may at a minimum impair the quality of life of these patients.[2] A nontoxic, inexpensive, readily available, and effective approach to this situation would be welcomed by patients and their caregivers.

Soybeans and their components have been studied extensively in prostate cancer research. A diet that is rich in soy has the potential to decrease the incidence of prostate cancer, and soy may modulate the disease process for established cancers.[3] In our clinical practice, we began to use commercially available soy milk as an alternative to observation in men with biochemical relapse of their prostate cancer. In addition, we have offered this therapy to select asymptomatic men with CR and low-volume disease as an initial treatment along with continued ADT in advance of the use of secondary hormonal manipulations and/or chemotherapy. We describe our experience in 10 men in clinical practice.

Comments

3090D553-9492-4563-8681-AD288FA52ACE
Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as:

processing....