Analysis of population characteristics related to the total effective xenoestrogen burden: a biomarker of xenoestrogen exposure in breast cancer.

To analyse the link between breast cancer and the combined effect of environmental xenoestrogens, we developed, standardised and applied a biomarker of exposure to assess the total effective xenoestrogen burden (TEXB) in human adipose tissue in a case-control study. Environmental oestrogens (TEXB-alpha) are separated from endogenous oestrogens (TEXB-beta), and the combined oestrogenic effect is determined from its proliferative effect (E-Screen assay). The aim of the study was to identify potential confounders, effect modifiers or other covariates associated with higher TEXB levels. In cases, age, family history of breast cancer, lactation experience and smoking were associated with TEXB-alpha. In controls, only age was associated with TEXB-alpha levels. In cases, age, educational level, age at menarche, menopausal status, marital status, lactation experience and smoking were associated with TEXB-beta. In controls, only menopausal status was significantly associated with TEXB-beta levels. In conclusion, TEXB, as a biomarker of exposure, takes account of environmental, dietary, lifestyle, genetic and reproductive factors, which are not usually systematically measured across studies.