Thyroid Dysfunction Following Conventional Anthracycline- and Taxane-based Chemotherapy for Breast Cancer

Abstract

Although thyroid disorders induced by immune checkpoint inhibitors (ICIs) and tyrosine kinase inhibitors (TKIs) have attracted much attention, little research has been done on thyroid dysfunction in conventional cancer treatment containing anthracyclines and taxanes. We retrospectively studied thyroid function in 61 patients who underwent conventional chemotherapy for breast cancer. Of the 61 patients, 17 (28%) developed thyroid dysfunction, including sub-clinical and overt hypothyroidism following chemotherapy, and 9 (15%) developed overt clinical hypothyroidism. Eight of the nine patients needed thyroid hormone replacement therapy with levothyroxine (L-T4). Taxane-based regimens tended to reduce free T4 levels and increase TSH levels more markedly compared to non-taxane-based regimens. Since the present study showed, for the first time, that conventional chemotherapy, as well as ICIs and TKIs, may induce hypothyroidism, it may be appropriate to evaluate thyroid function during chemotherapy. When patients show the clinical features of hypothyroidism, thyroid hormone replacement therapy merits consideration.