DPYD and head and neck squamous cell carcinoma: As all studies demonstrated the lasting value of PFE, we recommend—against the often suggested alternative use of TPE as unproblematic replacement for PFE to avoid potential dihydropyrimidine dehydrogenase- (DPD-) toxicity—rather DPD testing according to established guidelines (18) so that R/M HNSCC patients still can benefit from PFE.