Changes in the total effective xenoestrogen burden (TEXB) of breast cancer patients during an 18-month post-surgical follow-up.

We aimed to assess changes in the total effective xenoestrogen burden (TEXB) -a biomarker of combined effect of mixtures of xenoestrogens- in breast cancer patients at surgery (breast adipose tissue) and at different time points during an 18-month follow-up (abdominal adipose tissue), and to analyze the potential influence of socio-demographic, reproductive, tumor, and treatment characteristics on TEXB levels. TEXB-alpha (due to persistent organohalogenated chemicals) and TEXB-beta (due mainly to endogenous estrogens) were quantified in 44 women. TEXB values significantly increased over follow-up (p <0.001); the largest difference was observed at 6-12 months post-surgery (p <0.001); then decreased over time. TEXB-alpha at 6-18 months was significantly higher in younger patients with estrogen receptor positivity (p=0.034) and in those receiving anti-neoplasm chemotherapy. Cancer treatment may be responsible for the increase in TEXB-alpha observed in patients with hormone-dependent tumors, which may confer to xenoestrogens a role in the progression of the disease.