Lack of a correlation between γH2AX foci kinetics in lymphocytes and the severity of acute normal tissue reactions during IMRT treatment for head and neck cancer

Abstract

Purpose: To investigate the phosphorylated histone H2A isoform X (γH2AX) foci kinetics as an indicator for the development of acute normal tissue complications during Intensity-Modulated Radiotherapy (IMRT) for head and neck cancer (HNC) patients.

Materials and methods: Microscopic scoring of the γH2AX foci was used to evaluate the DNA-double-strand-break repair capacity in from Ataxia-Telangiectasia (A-T) patients derived lymphoblastoid cell lines (LCL) and T-lymphocytes isolated from 31 IMRT treated HNC patients. Cells were irradiated in vitro with 0.5 Gy given at high-dose-rate (HDR) and examined at several times up to 24 h after irradiation. The patients were subdivided in three groups showing mild, moderate and severe acute normal tissue complications based on their Common Toxicity Criteria grades for dysphagia, mucositis and dermatitis during the radiotherapy course.

Results: For the ATM (Ataxia-Telangiectasia-Mutated) defective LCL, a lower number of radiation-induced foci and a somewhat less efficient repair capacity was observed. No correlation was found between the γH2AX foci kinetics pattern and the risk for acute normal tissue complications among the three patient subgroups.

Conclusions: Scoring of γH2AX foci after in vitro irradiation of isolated T-lymphocytes of HNC patients cannot be applied to predict for the development of acute normal tissue complications.

Keywords:

• head and neck cancer
• γH2AX foci
• DNA DSB repair
• acute normal tissue complications
• radiosensitivity assay

Acknowledgements

The work was supported by a grant of the Bijzonder Onderzoeksfonds (Ghent University, No. 01D30006). We wish to thank all the patients who participated in this study. We are also grateful to the nursing staff of the department of Radiation Oncology at Ghent University Hospital for the collection of the patient blood samples.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.