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


South Med J. 2011;104(11):736-740. 

In This Article


The complete results for each of these patients are summarized in the Table. Seven of the men were white, two were African American and one was Asian American. The median age was 61 years. None of the men had gross metastatic disease as determined by bone scan or computed tomography scan and all of them were asymptomatic. All 10 men had a biochemical relapse after both prior RP and RT; 3 of the men also had rising PSA levels postmedical ADT in addition to prior RP and RT that was consistent with CR disease. Of the 10 men, 9 drank commercially available soy milk and 1 man (patient 8) preferred to eat the equivalent in soy snacks instead. All of the men reported that they enjoyed consuming the soy products and were compliant because they did not consider this nutriceutical intervention to be burdensome. Five of the men had frank progression on soy milk. Three men had reductions in PSA and negative PSA kinetics. One man had an attenuated PSA response with a decrease in PSA velocity and doubling time. One man had stable PSA and PSA kinetics. Overall, clinical benefits (decrease, attenuation, and stability of PSA) were noted in 5 of 10 (50%) patients. The median duration of response was 24 months. The individual results of the PSA kinetics in 2 of these men, patients 1 and 4, are represented in Figs. 1 and 2. Both of these men had good responses to the soy in terms of absolute PSA levels and PSA kinetics for significant periods of time. Patient 1 had a transient response that lasted about 24 months followed by progression back to baseline on continued soy. Patient 2 continues to respond to soy milk.

Figure 1.

Prostate-specific antigen kinetics in patient 1. Patient 1 experienced a steady decline in PSA on soy to a plateau that lasted approximately 2.5 years followed by subsequent progression on continued soy.

Figure 2.

Prostate-specific antigen kinetics in patient 4. Patient 4 experienced a steady decline in PSA, which lasted approximately 3 years.


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