Associations of Phthalates and Phenols, Telomere Length, and Breast Cancer in the Long Island Breast Cancer Study Project

Abstract

BACKGROUND AND AIM: Exposure to phthalates or phenols has been of concern as associated with breast cancer due to the endocrine disrupting effects of these chemicals. Studies related to the modifying role of cellular aging on these associations are lacking. We aim to evaluate the modifying effect of leukocyte telomere length (LTL), a biomarker of cellular aging, on the associations between phthalate and phenol exposure and breast cancer incidence and mortality. METHODS: We used data from 1268 women whose urinary phthalates and phenols and LTL measurements were available from the Long Island Breast Cancer Study Project. Twenty-two metabolites of phthalates and phenols were measured in the spot urine collected from the study participants. The modifying effect of LTL on the association between each individual metabolite and breast cancer incidence and mortality was estimated using interaction terms between LTL and the individual metabolites in logistic regression models and Cox regression models. Odds ratios, hazard ratios, and corresponding 95% confidence intervals (CI) for a one-unit (ln ug/g creatinine) increase of urinary metabolite concentration were estimated at 10th, 50th, and 90th percentiles of LTL. RESULTS:LTL significantly (P0.05) modified the associations between breast cancer incidence and metabolites for eleven phthalates and phenols. Metabolites were, in general, inversely and positively associated with breast cancer incidence at shorter and at longer LTL, respectively. No statistically significant modifying effect was found for LTL in the association between these metabolites and breast cancer mortality. CONCLUSIONS:Women with longer LTL were more susceptible to exposure to phthalates and phenols in the development of breast cancer. But shorter LTL can still increase the detrimental effect of certain types of phenols to breast cancer. KEYWORDS: Phthalate, Phenol, Breast Cancer, Leukocyte Telomere Length