Comparison of the comet assay and the oxygen microelectrode for measuring tumor oxygenation in head-and-neck cancer patients

Quynh Thu Le, Mary S. Kovacs, Mary Jo Dorie, Albert Koong, David J. Terris, Harlan A. Pinto, Don R. Goffinet, Kent Nowels, Dan Bloch, J. Martin Brown

Research output: Contribution to journalArticle

32 Scopus citations

Abstract

Purpose: To compare the Eppendorf PO2 histograph and the alkaline comet assay as methods of measuring tumor hypoxia in patients with head-and-neck squamous cell carcinomas. Materials and Methods: As part of a larger clinical trial, 65 patients with head-and-neck squamous cell carcinoma nodal metastasis underwent tumor oxygenation measurements with Eppendorf PO2 histographs and comet assays, performed on fine-needle aspirates at 1 and 2 min after 5 Gy. Fifty-four patients had sufficient tumor cells for comet analysis at 1 min and 26 at both 1 and 2 min. Individual cells were examined for DNA single-strand breaks by alkaline gel electrophoresis, and the distribution of values was quantified using median tail moment (MTM). Nonirradiated tumor cells from pretreatment fine-needle aspirates received 5 Gy in vitro to establish the oxygenated response. Results: There was a significant correlation between the 1- and 2-min MTM (slope = 0.77 ± 0.03). There was no relationship between DNA damage in tumor cells irradiated in vitro and in vivo. No correlation was found between Eppendorf PO2 measurements and comet MTM. There was a statistically significant correlation between the treatment response in the node studied and comet MTMs, whereas no correlation was observed between treatment response and Eppendorf measurements. Conclusion: Comet assays are reproducible, as shown by biopsies at 1 and 2 min. Intertumor variation in the MTM is not a result of intrinsic radiosensitivity but of tumor hypoxia. There was no correlation between Eppendorf PO2 measurements and comet MTM. Comet assays were better than Eppendorf in predicting treatment response as an end point for short-term outcome. Longer follow-up is needed to determine the role of the comet assay as a predictor for locoregional tumor control and survivals.

Original languageEnglish (US)
Pages (from-to)375-383
Number of pages9
JournalInternational Journal of Radiation Oncology Biology Physics
Volume56
Issue number2
DOIs
StatePublished - Jun 1 2003
Externally publishedYes

Keywords

  • Comet assay
  • Eppendorf microelectrode
  • Head-and-neck cancer
  • Hypoxia
  • Tumor oxygenation

ASJC Scopus subject areas

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

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