Table of Contents
ISRN Radiology
Volume 2013, Article ID 704659, 7 pages
http://dx.doi.org/10.5402/2013/704659
Clinical Study

Investigating γ H2AX as a Biomarker of Radiosensitivity Using Flow Cytometry Methods

1Environmental and Radiation Health Sciences Directorate, Health Canada, 775 Brookfield Road, Postal Locator 6303B, Ottawa, ON, Canada K1A 0K9
2Department of Physics, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada
3The Ottawa Hospital Cancer Centre, 501 Smyth Road, Ottawa, ON, Canada

Received 18 January 2013; Accepted 19 March 2013

Academic Editors: M. G. Andreassi and A. Sciarra

Copyright © 2013 Lindsay A. Beaton et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background and Purpose. This project examined the in vitro  γH2AX response in lymphocytes of prostate cancer patients who had a radiosensitive response after receiving radiotherapy. The goal of this project was to determine whether the γH2AX response, as measured by flow cytometry, could be used as a marker of individual patient radiosensitivity. Materials and Methods. Patients were selected from a randomized clinical trial evaluating the optimal timing of Dose Escalated Radiation and short-course Androgen Deprivation Therapy. Of 438 patients, 3% developed Grade 3 late radiation proctitis and were considered to be radiosensitive. Blood was drawn from 10 of these patients along with 20 matched samples from patients with Grade 0 proctitis. Dose response curves up to 10 Gy along with time response curves after 2 Gy (0–24 h) were generated for each sample. The γH2AX response in lymphocytes and lymphocyte subsets was analyzed by flow cytometry. Results. There were no significant differences between the radiosensitive and control samples for either the dose course or the time course. Conclusions. Although γH2AX response has previously been demonstrated to be an indicator of individual patient radiosensitivity, flow cytometry lacks the sensitivity necessary to distinguish any differences between samples from control and radiosensitive patients.