Lifestyle factors and urine levels of organophosphorus flame retardants in endometrial cancer: insights from a case-control study

Background: Organophosphate flame retardants (OPFRs) are commonly used in various consumer products to prevent fire hazards. However, OPFRs have been linked to several health problems, including cancer. This study aimed to investigate the association between urine levels of OPFRs and endometrial cancer (EC), and to explore the correlation between concentrations of parent OPFR compounds and their metabolites. Methods: Urine samples from 76 EC patients and 76 healthy controls were collected and analyzed for the levels of five common parent OPFRs and their respective metabolites. Propensity score matching was applied to account for differences in baseline characteristics between the two participant groups. Significantly higher levels of OPFRs in EC patients were identified, and logistic regression models were used to determine whether elevated OPFRs were associated with EC and to explore whether any lifestyle behaviors contributed to the increased OPFR levels. Spearman’s rank correlation coefficients between the concentrations of the parent compounds and their metabolites were calculated. Results: Out of the ten OPFRs studied, the median urine levels of bis(1,3-dichloro-2-propyl) phosphate (BDCPP), tris(2-butoxyethyl) phosphate (TBEP), and di-(2-butoxyethyl) phosphate (DBEP) were significantly higher in EC patients compared to healthy controls. After matching 41 patients with 41 controls, multiple logistic regression analysis revealed that only BDCPP (OR 4.274; 95% CI 1.172–15.592) was an independent factor associated with EC. A lifestyle questionnaire survey found that urine BDCPP levels were related to age (OR 4.294; 95% CI 1.015–18.164), meals eaten out (OR 4.238; 95% CI 1.454–12.354), and consumption of chilled-ready meals (OR 0.118; 95% CI 0.014–0.985). A positive correlation was only observed between the concentrations of TBEP and its metabolite DBEP; other correlations were not significant. Conclusion: We concluded that higher urine BDCPP level was an independent factor associated with EC, and higher BDCPP levels were related to aging, more meals eaten out, and fewer chilled-ready meals. These findings highlight the potential hazard of long-term OPFR exposure on the development of EC.