Nutritional supplement with fermented soy in men with an elevated risk of prostate cancer and negative prostate biopsies: General and oncological results from the prospective PRAECAP trial.

INTRODUCTION & OBJECTIVES: To investigate the effect of a dietary supplement containing fermented soy on PSA, IPSS, changes in prostate volume and prostate cancer development after a 6-month challenge in men at increased risk of prostate cancer and negative previous biopsies.

MATERIALS & METHODS: Patients with an elevated risk of PCa, defined by either 1 of the following criteria: PSA > 3 ng/ml, suspect lesion at digital rectal examination (DRE), suspect lesion at transrectal ultrasound (TRUS) / magnetic resonance imaging (MRI) and previous negative prostate biopsies (at least 8 cores) within 12 months before inclusion. Statistical analysis was carried out using a non-parametric one-sided paired Wilcoxon rank sum test, chi-square test and Fisher's exact test.

RESULTS: In this trial, 94 patients where eligible for analysis. A PSA response was detected in 81% of the cases. In 25.8% (24/93) of patients, a decrease of at least 3 points on the IPSS was observed. The median prostate volume did not statistically change after 6 months (p=0.908). Patients with PSA modulation required fewer investigations and had fewer positive biopsies (p<0.001) and significantly fewer ISUP≥3 lesions (p=0.02).

CONCLUSIONS: We observed a significantly lower PSA level after a 6-month challenge with a fermented soy-containing supplement, and an effect on IPSS in a subset of patients. Prescribing a fermented soy supplement in patients with an increased PCa risk could lead to a better selection of patients at real increased risk of having occult PCa.