Abstract: Objective To investigate the short-term effect of chemotherapy on thyroid function or structure in patients with breast cancer. Methods Forty female patients with primary breast cancer treated in the first affiliated Hospital of Bengbu Medical College from March 2017 to December 2018 were selected. The changes of thyroid function (including T3, T4, FT3, FT4 and TSH) and their structure were measured and compared between before and after chemotherapy for two and four cycles. Results The levels of T4 and FT4 were significantly lower in breast cancer patients receiving either two or four cycles of chemotherapy than those receiving no chemotherapy(P＜0.05); and the levels of thyroid TI-RADS grade and the incidence of abnormal thyroid structure were significantly higher in patients receiving four courses of chemotherapy than those receiving no chemotherapy (P＜0.05). Conclusions In the near future,the event of chemotherapy can cause or aggravate abnormal thyroid function or structure in patients with breast cancer. Regular physical examination and necessary intervention have important clinical significance to prevent the development of thyroid disease.

Key words: breast cancer, chemotherapy, thyroid function, thyroid structure