title: Capecitabine therapy for refractory metastatic thyroid carcinoma: a case series.
abstract: OBJECTIVE
  There are few effective therapies for metastatic medullary (MTC) or radioiodine-resistant follicular thyroid carcinomas (FTC). We report a single institution's experience with capecitabine, a thymidylate synthase (TS) inhibitor, in the treatment of MTC and FTC.
  
  
  METHODS
  We retrospectively analyzed five cases of metastatic thyroid carcinoma, three MTCs and two radioiodine-resistant FTCs, treated with capecitabine alone or in combination with other chemotherapeutics. Patients were selected for treatment based on low tumor TS immunohistochemical staining (< or =5%). Staining for thymidylate phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) was also performed. Therapeutic response was assessed by imaging studies and serum tumor markers: calcitonin and carcinoembryonic antigen (MTC), and thyroglobulin (FTC).
  
  
  RESULTS
  Two of three patients with MTC had stable disease or disease regression on capecitabine. One of these patients had a 90% reduction in calcitonin and stabilization by imaging that lasted 4 years. Both patients with FTC initially had stable disease on capecitabine. One patient, who was treated with capecitabine in combination first with doxorubicin and then etoposide, had an initial decrease in tumor burden, followed by stable disease for 2.8 years. The second patient had stable disease, but capecitabine was discontinued after 11 months because of hand/foot syndrome.
  
  
  CONCLUSIONS
  This series demonstrates promising results for the use of capecitabine in treatment of MTC and radioiodine-resistant FTC, for which there is a limited repertoire of therapeutic agents. Larger studies are needed to confirm these findings and to establish the role of fluoropyramidine metabolism markers in predicting response.
authors.affiliation: Divisions of Metabolism, Endocrinology and Nutrition, University of Washington, Seattle, Washington 98195, USA. lgilliam@u.washington.edu
authors.forename: Lisa K
authors.initials: LK
authors.lastname: Gilliam
authors.forename: Aimee D
authors.initials: AD
authors.lastname: Kohn
authors.forename: Tasneem
authors.initials: T
authors.lastname: Lalani
authors.forename: Paul E
authors.initials: PE
authors.lastname: Swanson
authors.forename: Vasyl
authors.initials: V
authors.lastname: Vasko
authors.forename: Aneeta
authors.initials: A
authors.lastname: Patel
authors.forename: Robert B
authors.initials: RB
authors.lastname: Livingston
authors.forename: Cheryl A
authors.initials: CA
authors.lastname: Pickett
mesh_terms: D000328:Adult; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D000069287:Capecitabine; D002272:Carcinoembryonic Antigen / Q000378:metabolism; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D042943:Dihydrouracil Dehydrogenase (NADP) / Q000378:metabolism; D005260:Female; D005472:Fluorouracil / Q000031:analogs & derivatives* / Q000627:therapeutic use; D006801:Humans; D007457:Iodine Radioisotopes / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D012189:Retrospective Studies; D013939:Thymidine Phosphorylase / Q000378:metabolism; D013954:Thyroglobulin / Q000378:metabolism; D013964:Thyroid Neoplasms / Q000188:drug therapy*
chemical_list: D000964:Antimetabolites, Antineoplastic; D002272:Carcinoembryonic Antigen; D007457:Iodine Radioisotopes; D003841:Deoxycytidine; D000069287:Capecitabine; D013954:Thyroglobulin; D042943:Dihydrouracil Dehydrogenase (NADP); D013939:Thymidine Phosphorylase; D005472:Fluorouracil