title: Hypoxia inducible factor (HIf1alpha and HIF2alpha) and carbonic anhydrase 9 (CA9) expression and response of head-neck cancer to hypofractionated and accelerated radiotherapy.
abstract: OBJECTIVE
  Tumor hypoxia and low intrinsic radiosensitivity may counteract the efficacy of standard radiotherapy for locally advanced head and neck cancer (HNC). We investigated the involvement of hypoxia-regulated proteins (Hypoxia inducible factors HIF1alpha, HIF2alpha and carbonic anhydrase CA9) in HNC resistance to accelerated and hypofractionated radiotherapy.
  
  
  METHODS
  Thirty-nine patients with locally advanced HNC received 15 daily fractions of 3.4 Gy amounting to a total tumor dose of 51 Gy (equivalent to 63 Gy in four weeks--one week split); this was combined with platinum chemotherapy and amifostine cytoprotection administered subcutaneously. Immunohistochemical analysis of hypoxia-regulated proteins, namely HIF1alpha, HIF2alpha and CA9, was performed in formalin-fixed paraffin-embedded tissues obtained prior to radio-chemotherapy.
  
  
  RESULTS
  HIF1alpha and HIF2alpha were expressed in the nuclei and cytoplasm of cancer cells, while CA9 had a membrane reactivity. A high expression of HIF1alpha, HIF2alpha and CA9 was noted in 21/39 (53.8%), 20/39 (51.3%) and 23/39 (58.9%) cases, respectively. Complete response was obtained in 85.2% of patients and HIF1alpha was marginally related with persistent disease after RT (p = 0.05). HIF1alpha was significantly associated with poor local relapse free survival (LRFS) (p = 0.006) and overall survival (p = 0.008), whilst HIF2alpha was not. A significant association of CA9 expression with poor LRFS was noted (p = 0.01).
  
  
  CONCLUSIONS
  In accord with previously reported studies, high levels of the hypoxia regulated proteins HIF1alpha and CA9 in HNC predict resistance to platinum based radio-chemotherapy. Whether HIF2alpha expressing tumors are more sensitive to larger radiotherapy fractions, compared to standard radiotherapy fractionation, is an issue that deserves further investigation.
authors.affiliation: Department of Radiotherapy/Oncology, Democritus University of Thrace, University Hospital of Alexandroupolis, Alexandroupolis, Greece. targ@her.forthnet.gr
authors.forename: Michael I
authors.initials: MI
authors.lastname: Koukourakis
authors.forename: Alexandra
authors.initials: A
authors.lastname: Giatromanolaki
authors.forename: Vassilios
authors.initials: V
authors.lastname: Danielidis
authors.forename: Efthimios
authors.initials: E
authors.lastname: Sivridis
mesh_terms: D004999:Amifostine / Q000627:therapeutic use; D000951:Antigens, Neoplasm / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000627:therapeutic use; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000378:metabolism*; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases / Q000378:metabolism*; D015687:Cell Hypoxia; D002462:Cell Membrane / Q000378:metabolism / Q000473:pathology; D002467:Cell Nucleus / Q000378:metabolism / Q000473:pathology; D003131:Combined Modality Therapy; D003593:Cytoplasm / Q000378:metabolism / Q000473:pathology; D019610:Cytoprotection; D019583:Dose Fractionation, Radiation; D006258:Head and Neck Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D009364:Neoplasm Recurrence, Local / Q000517:prevention & control; D009944:Organoplatinum Compounds / Q000627:therapeutic use; D011446:Prospective Studies; D011836:Radiation Tolerance; D011837:Radiation-Protective Agents / Q000627:therapeutic use; D020266:Radiotherapy, Conformal; D000099162:Endothelial PAS Domain-Containing Protein 1
chemical_list: D004999:Amifostine; D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; D051792:Basic Helix-Loop-Helix Proteins; D014408:Biomarkers, Tumor; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009944:Organoplatinum Compounds; D011837:Radiation-Protective Agents; D000099162:Endothelial PAS Domain-Containing Protein 1; C089226:CA9 protein, human