title: Case report of acquired piritrexim resistance and collateral methotrexate sensitivity in recurrent squamous cell carcinoma of the head and neck.
authors.forename: E
authors.initials: E
authors.lastname: Cvitkovic
authors.forename: C
authors.initials: C
authors.lastname: Domenge
authors.forename: D
authors.initials: D
authors.lastname: Gandia
mesh_terms: D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy*; D004351:Drug Resistance; D005493:Folic Acid Antagonists / Q000627:therapeutic use*; D006258:Head and Neck Neoplasms / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008727:Methotrexate / Q000627:therapeutic use*; D009364:Neoplasm Recurrence, Local / Q000188:drug therapy; D011743:Pyrimidines / Q000627:therapeutic use*
chemical_list: D000970:Antineoplastic Agents; D005493:Folic Acid Antagonists; D011743:Pyrimidines; C024530:piritrexim; D008727:Methotrexate