Soy Isoflavone Supplementation and Biochemical Recurrence After Curative Treatment for Localized Prostate Cancer

Abstract

Background: Despite an abundance of soy interventions, the effect of soy isoflavones prior to curative treatment for localized prostate cancer on biochemical recurrence has not been evaluated. Objective: To determine if short-term supplementation with soy isoflavones prior to curative treatment delays or prevents biochemical recurrence in men with localized prostate cancer. Design: Electronic medical record reviews were conducted in February 2013 to gather follow-up data on men (n = 86) previously enrolled in the Role of Isoflavones in Prostate Cancer study. Data collected included demographics, treatment modalities and complications, clinical and pathological staging, Gleason score, body mass index (BMI), comorbidities, prostate-specific antigen (PSA), PSA recurrence, time to recurrence, and death status. Fisher Exact test was used to compare rates of biochemical recurrence. Mann-Whitney U test was used to compare time to recurrence. Time to event analyses were performed using Kaplan-Meier plots with Log-rank test applied to assess statistical significance. Logistic regression analysis using PSA recurrence (yes/no) as a response was used adjusting for age and race. Results: Sixty-six men were included in the final analysis. p Conclusion: Short-term supplementation with soy isoflavones prior to curative treatment for localized prostate cancer was not found to significantly affect biochemical recurrence in this study.