A Case of Recurrent Metastatic Parotid Acinic Cell Carcinoma Responsive to Pembrolizumab

Abstract

Background: No clear chemotherapy regimen for recurrent or metastatic parotid cancer exists. We describe our experience with pembrolizumab to treat recurrent or metastatic parotid cancer. Case Report: A 73-year-old woman with swelling in the lower part of the right ear for 10 years before surgery was diagnosed with right parotid cancer, underwent total right parotidectomy, and reported recurrence. She requested treatment due to diminished quality of life caused by neurological symptoms. Tissue was collected from the recurrent lesion and its combined positive score was >20; pembrolizumab was started 9 years postoperatively. Results: To date, the patient has received 14 cycles of pembrolizumab. Evaluation by computed tomography showed a partial response to treatment. The only immune-related adverse event was grade 1 pneumonia in both lungs. Conclusion: Significant response to pembrolizumab in recurrent or metastatic parotid cancer is rarely reported, making this a remarkable case. We plan to continue pembrolizumab administration.