Abstract: Thyroid metastases secondary to triple-negative breast cancer are sporadic. Diagnosis usually requires fine needle aspiration biopsy (FNAB) and immunohistochemistry. There are no treatment guidelines for this type of cancer, and to date, reports of chemotherapy combined with immunotherapy in thyroid metastases are very rare. Here, we first report the effectiveness of anti-PD-1 inhibitor in combination with chemotherapy for the treatment of metastatic thyroid cancer secondary to advanced triple-negative breast cancer with high expression of programmed cell death ligand 1 (PD-L1). Following six cycles of albumin paclitaxel (400mg d1/21 days) plus PD-1 antibody inhibitor (Sindilizumab 200mg d1/21 days), the patient experienced significant relief of neck swelling and obstructive feeding, both the thyroid metastases and the right breast lesion regressed completely following six cycles of treatment. Chemotherapy combined with immunotherapy may provide a new direction for unresectable advanced thyroid metastases.

Keywords: thyroid metastases, triple-negative breast cancer, albumin paclitaxel, anti-PD-1 inhibitor, effectiveness