Endocrine disruptive chemicals and thyroid cancer: a review

Abstract

Background/Aim: Endocrine disruptive chemicals (EDCs) are known to alter thyroid hormone function and have been associated with increased risk of certain cancers. The present study aims at providing a comprehensive review of available epidemiologic studies on the association between EDC exposure and thyroid cancer.Methods: A PubMed search was performed including the following terms in different combinations: thyroid cancer, endocrine disrupting chemicals or endocrine disruptors, pesticides, and specific EDCs including but limited to heavy metals, flame retardants, polychlorinated biphenyls (PCBs), phthalates, perfluoroalkyl acid (PFAS) and bisphenol A (BPA), to identify relevant publications.Results: The most consistent association was found between heavy metal exposure and thyroid cancer; multiple studies reported a positive association between high levels of cadmium and thyroid cancer. There were some indications for an association with lead. Although multiple studies have been reporting on pesticide exposure and thyroid cancer, the inclusion of different pesticides and mixtures impedes a conclusion. A suggestive association between flame retardants and thyroid cancer has been reported, however the number of studies is limited. Although PCB exposure has been associated with breast cancer, thyroid cancer has not been well researched. To date, some studies suggested an association between phthalate or BPA exposure and thyroid cancer however studies had limitations and results were conflicting. Although PFAS has been associated with thyroid disruption, studies on the association with thyroid cancer are still lacking.Conclusion: Overall, there is a suggestive association between exposure to certain EDCs and thyroid cancer. The lack of and the conflicting results highlight the importance of additional research needed to investigate the role of EDC exposure in in thyroid carcinogenesis and underlying mechanisms.