Soy Consumption and the Risk of Prostate Cancer in Men: An Updated Systematic Review and Meta‐analysis
Authors: Applegate Catherine C , Rowles Joe L , Ranard Katherine M , Jeon Sookyoung , Erdman John W 
Published: November 2023

Background

Prostate cancer (PCa) is the third most commonly diagnosed cancer and the sixth most common cause of cancer‐related deaths in the United States. Worldwide, PCa is the second most commonly diagnosed cancer and the fifth leading cause of cancer‐related deaths. PCa incidence is higher in more developed countries, with Australia/New Zealand and North America having the highest rates, while rates remain lowest in Asian countries. The lower incidence of PCa in Asian populations has been associated with the consumption of soy foods. Soy has been under intensifying scrutiny in recent years for its potential role in the prevention of hormone‐driven cancers. The purpose of this study is to provide an updated systematic review and meta‐analysis focused on the association of soy foods on the risk of PCa in men.

Methods

A systematic review and meta‐analysis to determine the influence of soy food consumption on the risk of PCa in men is currently underway. Eligible studies were published before October 10, 2016 and were identified from PubMed, Web of Science, and the Cochrane Library. Articles were identified using the following key words and their variants: prostate cancer, prostate neoplasm, soy, soymilk, soy milk, isoflavone, bean curd, tofu, soy protein, daidzein, and genistein. For studies to have been included in this meta‐analysis, they must have met the following criteria: (a) evaluated the association between soy food consumption and PCa risk by using randomized control trials and cohort, cross‐sectional, retrospective, prospective, or case‐control studies; (b) methodology was documented in replicable detail; (c) evaluated the relationship between soy and prostate cancer risk; (d) included relative risk ratio with 95% confidence intervals for exposure categories; (e) were written in English; and (f) peer‐reviewed publications or theses. We will utilize a Newcastle‐Ottawa Scale in order to assess the quality of this data. Additionally, data from included articles were utilized for comparisons of highest to lowest consumption, dose‐response relationships, and for potential publication bias. From these comparisons, we will estimate pooled relative risk ratios (RR) and 95% confidence intervals (CI) using random and fixed effects models.

Results

After screening the literature, a total of 3,309 articles were identified. Eight hundred and thirty‐six articles were immediately removed as duplicates. Of the 2,473 remaining articles, 2,444 were removed through the abstract screening process, and 29 articles were identified for full‐text review. After reviewing the full text, 22 articles met the inclusion criteria and will be analyzed in the meta‐analysis.

Significance

Data gleaned from this study will result in an updated systematic review and meta‐analysis of the effect of soy consumption on the risk of PCa, providing support or nonsupport for the potential beneficial effect of increased soy food consumption on PCa risk.