Published in the Red Journal, this study tried to identify biological factors that may yield a therapeutic advantage of proton therapy versus photon therapy. Specifically, the role of non-homologous end-joining (NHEJ) and homologous recombination (HR) in the survival of cells in response to clinical photon and proton beams. With the tested cell lines, the results indicate that NHEJ deficiency is more important in dictating cell survival than proton LET.

Cells with disrupted HR through BRCA1 mutation showed increased radiosensitivity only for high-LET protons. This study highlights the importance of tumor biology in dictating treatment modality, as well as suggesting BRCA1 as a potential biomarker for proton therapy response.