Association between soy products and prostate cancer: A systematic review and meta-analysis of observational studies.

Wenyan Wang, Yiping Huang, Jianxiang Jin

Journal: Investigative and clinical urology 2024;65(6):540-550

PMID: 39505513

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Plain Language Summary

This systematic review and meta-analysis examined the relationship between soy products and prostate cancer (PCA), a type of cancer affecting the prostate gland in men. Researchers analysed data from 22 studies involving over 1.4 million participants to determine if consuming soy products could influence the risk of developing PCA.

The study used statistical methods to calculate the likelihood of developing PCA among those who consume soy compared to those who do not. The results showed that people who consumed soy products had a slightly lower risk of developing PCA compared with those who consumed less or no soy. However, this protective effect was specific to localised or low-grade PCA and was not observed for non-localised or high-grade PCA. The association also varied by ethnicity as a significant reduction in PCA risk was found in African Americans and Latinos, but not in Japanese, Chinese, or White populations.

In conclusion, this study suggests a potential protective association between soy consumption and PCA risk. However, this appears to be limited to localised or low-grade disease and may vary across ethnic groups. Healthcare professionals may use these findings to inform dietary discussions with patients, while recognising that the evidence does not apply to all forms of PCA or all populations.

Abstract

PURPOSE

The effect of soy products on prostate cancer (PCA) remains a topic of debate. This study aimed to investigate the association between soy products consumption and the incidence of PCA.

MATERIALS AND METHODS

A search was conducted in the PubMed, EBSCO, Web of Science, and Cochrane Library databases up to December 2023. The adjusted odds ratio (OR) and corresponding 95% confidence interval (CI) were used to assess the association.

RESULTS

A total of 22 articles, comprising 1,409,213 participants, were included for this meta-analysis. The results indicate that soy products reduce the risk of PCA (OR=0.94, 95% CI=0.91-0.97, p<0.001), especially in cases of localized or low-grade PCA (OR=0.94, 95% CI=0.90-0.97, p<0.001), but exhibit no effect on non-localized or high-grade PCA (OR=0.96, 95% CI=0.91-1.01, p=0.085). Furthermore, increased consumption frequency was negatively associated with PCA risk. Specifically, soy products can reduce the risk of PCA in African Americans (OR=0.89, p=0.006) and Latinos (OR=0.93, p=0.036), but have no impact on Japanese (OR=0.99, p=0.655), Chinese (OR=0.90, p=0.155), and Whites (OR=0.96, p=0.133). Non-fermented soy products were associated with a reduction in the incidence rate of PCA (OR=0.93, 95% CI=0.90-0.96, p<0.001), while fermented soy products had no effect on the incidence rate of PCA (OR=1.10, 95% CI=0.98-1.22, p=0.096).

CONCLUSIONS

The consumption of soy products can reduce the overall risk of PCA among men. Various factors, including soy products-related factors (e.g., consumption, frequency), population-related factors (e.g., race), and PCA-related factors (e.g., PCA stage) collectively influence the effect of soy products on PCA.

Address: Department of Urology, Affiliated Jinhua Hospital, Zhejiang University School of Medicine, Jinhua, China.; School of Pharmaceutical Sciences, Key Laboratory of Biotechnology and Pharmaceutical Engineering, Wenzhou Medical University, Wenzhou, China.; Affiliated Jinhua Hospital, Zhejiang University School of Medicine, Jinhua, China. [email protected].

DOI: 10.4111/icu.20240186