How would you treat recurrent parotid gland carcinoma with unresectable, metastatic disease?  

It depends on the histology. Salivary ductal carcinomas are often HER2 positive, and I have had some success treating with HER2 targeted regimens. Secretory carcinomas often have NTRK fusions, and should be enrolled on clinical trials with NTRK inhibitors if possible (Drilon A et al, NEJM, 2018). ...