title: Is glutathione-S-transferase-pi expression a reliable predictor of chemoradiation response in cancer of the head and neck?
abstract: OBJECTIVE
  Concurrent radiation and chemotherapy is being evaluated as an alternative treatment to surgery for patients with advanced squamous cell carcinoma of the head and neck, because organ preservation maybe possible without compromising survival. However, the response to concurrent chemoradiation treatment varies from patient to patient, and there is currently no available molecular predictor of response for this particular treatment modality. There is some evidence to indicate that glutathione S-transferase-pi (GST-pi), which is one of the drug detoxifying enzymes, may decrease the effectiveness of platinum-based chemotherapy in the treatment of a variety of tumor types. This study was performed to investigate whether GST-pi expression was correlated with response to concurrent chemotherapy and radiotherapy in patients with advanced squamous cell carcinoma of the head and neck.
  
  
  METHODS
  Diagnostic biopsy specimens of 36 patients who underwent concurrent chemoradiotherapy for the treatment of advanced squamous cell carcinoma of the head and neck were examined for GST-pi expression by using immunohistochemistry with polyclonal antihuman GST-pi antibodies. GST-pi expression scores were compared among responders and nonresponders.
  
  
  RESULTS
  Although the staining rate with antiGST-pi was slightly lower in the responder group in comparison with the nonresponders (82% vs 100%), the difference was not statistically significant.
  
  
  CONCLUSIONS
  GST-pi expression is unlikely to be a valuable predictor of response to concurrent chemotherapy and radiation treatment in patients with advanced squamous cell carcinoma of the head and neck.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
authors.forename: E
authors.initials: E
authors.lastname: Vural
authors.forename: M
authors.initials: M
authors.lastname: Alexiou
authors.forename: J
authors.initials: J
authors.lastname: Hunt
authors.forename: S
authors.initials: S
authors.lastname: Korourian
authors.forename: E
authors.initials: E
authors.lastname: Hanna
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000378:metabolism / Q000532:radiotherapy; D003131:Combined Modality Therapy; D005260:Female; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase / Q000378:metabolism*; D006258:Head and Neck Neoplasms / Q000737:chemistry / Q000378:metabolism / Q000532:radiotherapy; D006801:Humans; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011879:Radiotherapy Dosage
chemical_list: D007527:Isoenzymes; C496556:GSTP1 protein, human; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase