Prostate Cancer: Soy Supplementation Did Not Reduce Recurrence

Maarten C. Bosland, DVSc, PhD Professor of Pathology Department of Pathology University of Illinois at Chicago College of Medicine Chicago, IL 60612 MedicalResearch.com Interview with:
Maarten C. Bosland, DVSc, PhD

Professor of Pathology
Department of Pathology
University of Illinois at Chicago
College of Medicine
Chicago, IL 60612

MedicalResearch.com: What are the main findings of the study?

Dr. Bosland: Daily consumption of a supplement containing soy protein isolate for two years following radical prostatectomy did not reduce recurrence of prostate cancer in men at high risk for this (radical prostatectomy is surgical removal of the prostate to treat prostate cancer). The study showed that this soy supplementation was safe. It is not clear whether this result indicates that soy does not prevent the development of prostate cancer, but men that have the disease probably do not benefit from soy supplementation.

MedicalResearch.com: Were any of the findings unexpected?

Dr. Bosland:: The hypothesis was that soy supplementation reduces prostate cancer recurrence, based on epidemiologic findings and data from animal studies. Thus, the finding of a lack of treatment effect was unexpected.

MedicalResearch.com: What should clinicians and patients take away from your report?

Dr. Bosland: Men should not expect benefit from consuming soy after initial surgical treatment for prostate cancer. Men who have received radiation treatment may also not benefit from soy. Men who consume soy for their entire life may have a reduced risk of developing detectable prostate cancer (but this cannot be studied in a clinical trial). The study results indicate that long-term soy consumption does appear to be safe. It is not clear whether soy is of benefit to men who have advanced prostate cancer and are receiving hormonal treatment or chemotherapy and whether it is safe for these men.

MedicalResearch.com: What recommendations do you have for future research as a result of this study?

Dr. Bosland: It would be useful to determine the benefit and safety of soy supplements in men who have advanced prostate cancer and are receiving hormonal treatment or chemotherapy in rigorous randomized clinical trials. It is important to also rigorously test other dietary supplements commonly used by men with prostate cancer for benefit and safety randomized clinical trials.

Citation:

Effect of Soy Protein Isolate Supplementation on Biochemical Recurrence of Prostate Cancer After Radical Prostatectomy
A Randomized Trial

Bosland MC, Kato I, Zeleniuch-Jacquotte A, et al. Effect of Soy Protein Isolate Supplementation on Biochemical Recurrence of Prostate Cancer After Radical Prostatectomy: A Randomized Trial. JAMA. 2013;310(2):170-178. doi:10.1001/jama.2013.7842.