High BPA levels linked to increased prostate cancer risk in older men

By Hugo Francisco de SouzaReviewed by Susha Cheriyedath, M.Sc.Aug 8 2024

In a recent study published in the journal Nutrients, researchers investigated the associations between urinary bisphenol A (BPA) concentrations (exposure) and the prostate-specific antigen (PSA; outcome). They utilized a cohort of 2,768 elderly male Americans derived from the National Health and Nutrition Examination Survey (NHANES) between 2003 and 2012 for their examination.

A battery of statistical analyses comprising regressions (weighted linear and logistic), natural cubic spline (NCS), and interaction models revealed that BPA was positively correlated with PSA and, in turn, prostate cancer. These findings suggest the need for intensive prostate cancer screening in elderly male Americans (>75 years), especially those with high urinary BPA concentrations.

Study: Association between Bisphenol A and Prostate-Specific Antigen (PSA) among U.S. Older Males: National Health and Nutrition Examination Survey (NHANES), 2003–2012. Image Credit: Julien Tromeur / Shutterstock

Background

Prostate cancer is a male-specific disease characterized by abnormal cell/tissue growths originating from the walnut-sized prostate gland, the organ responsible for secreting seminal fluid. Prostate cancer is a severe and often life-threatening disease. Alarmingly, the prevalence of the condition, particularly in developed nations, is increasing at an unprecedented rate. In 2020 alone, 191,930 novel cases were identified in the United States (US), claiming 10.4% of all cancer-associated deaths.

Previous research has aimed to identify risk factors associated with the disease and has thus far highlighted the roles of environmental endocrine disruptors in the genesis and progression of the condition. One such disruptor, bisphenol A (BPA), has been singled out as a global health concern given its ubiquitous prevalence in daily-use plastics and food packaging materials and its detrimental impacts on brain and prostate physiology. Endocrinological research suggests that BPA can interact with estrogen receptor-α (ER-α), a prostate-expressed hormone, thereby promoting the growth and proliferation of prostate cancers.

Unfortunately, studies aimed at investigating this association have produced conflicting results. While in vivo murine models and some human clinical trials have not found evidence for BPA-enhanced prostate cancer growth, others have established a link between these variables. Since serum concentrations of the prostate-specific antigen (PSA) are commonly used diagnostic tools in early prostate cancer diagnosis, investigating the link between BPA, PSA, and, in turn, prostate cancer may help identify high-risk populations, thereby saving thousands of future lives.

About the study

The present study utilizes data from a long-term, US nationally representative cohort called the National Health and Nutrition Examination Survey (NHANES). For this study, data collection was restricted between 2003 and 2012 and included elderly American men (>50 yrs) with individuals without complete demographic or BPA datasets excluded.

Collected data comprised urinary BPA concentrations, PSA concentrations, sociodemographic data, and medical health records. For statistical analyses, BPA concentrations were considered the independent variable, PSA concentrations comprised the dependent variable, and sociodemographic/medical data (e.g., smoking status, race/ethnicity, age, body mass index [BMI], cholesterol, and poverty income ratio [PIR]) were used as confounders.

Prostate cancer risk was defined per the US Centers for Disease Control and Prevention (CDC) guidelines – PSA < 4 ng/mL comprised ‘low cancer risk,’ while PSA ≥ 4 ng/mL was classified as ‘high cancer risk.’ Statistical analyses included regression models (weighted linear and logistic), subgroup analysis, natural cubic spline (NCS), and interaction analysis.

Study findings

Of the 53,700 NHANES participants initially screened, 2,738 met the study inclusion criteria and were included in the subsequent analyses. The mean age of the study cohort was 62.70 years and predominantly comprised non-Hispanic white individuals. Urinary BPA concentrations were categorized into four quartiles (Q1-Q4) for ease of analysis and outcome reporting.

Weighted linear regression analysis highlights a positive correlation between BPA and PSA concentrations, with every unit increase in BPA associated with a 2.760 ng/mL increase in PSA. Alarmingly, logistic regressions revealed that in participants categorized as ‘high cancer risk,’ every unit increase in BPA concentrations resulted in a 42.5% increase in prostate cancer genesis. Together, these findings establish the association between BPA and PSA and, in turn, prostate cancer.

Subgroup analysis revealed that cancer risk was highest in individuals aged 75 years and above, those with PIR between 0-1, low education levels, and BMI < 25. Non-Hispanic black individuals were also found to be at greater risk than other ethnicities.

“Patients who have hypertension and cancer have a higher risk of prostate cancer as the concentration of BPA increases. In addition, we found interactions between urinary BPA and age, PIR, education, glycohemoglobin, HDL, smoking status, and diabetes (p for interaction < 0.05.”

Conclusions

The present study establishes the association between BPA, PSA, and prostate cancer. A unit increase in urinary BPA concentrations was observed to increase PSA concentrations by 2.760 ng/mL, corresponding to between 42.5% and 72% increase in the subsequent risk of prostate cancer.

Furthermore, this study identified high-risk populations within the NHANES study and, by extension, the US. senior men (>75 years), economically and educationally backward, and non-Hispanic Black individuals were found to be at the highest risk of prostate cancer. While this highlights a need for intensive cancer screening in these populations, the predominance of non-Hispanic white participants in the analysis dataset presents a need for further studies with different races/ethnicities to substantiate these findings.