Collaborative research led by the University of Liverpool has identified the specific cellular process that helps cancer cells repair damage resulting from proton beam therapy (PBT), determining that low energy treatments are more effective in the battle against cancer.

PBT is a type of radiation treatment that uses protons generated in a synchrotron or cyclotron to treat cancer. The protons’ speed determines the energy level, with high energy protons traveling deeper in the body than low energy ones. The key advantage of PBT is that it can deliver the radiation dose specifically to a tumor and limits damage to normal, healthy tissue.

“Our research shows that protons at different energies display distinct effects on DNA which have a major impact on their efficiency in causing cancer cell killing,” says Dr. Jason Parsons from the University of Liverpool’s Institute of Translational Medicine. “Low energy protons cause increases in complex DNA damage, which contributes significantly to decreased cell survival versus high energy protons and conventional X-ray irradiation.”

In the study, Parsons’ team treated a number of different cancer cells to both high energy and low energy protons and measured the levels of complex DNA damage and how the cancer cells initiate the repair that correlates to their survival. The team found that low energy protons, in comparison to high energy protons, introduced increased levels of damage to the DNA that persists in the cells and contributes significantly to the cell killing effects of PBT.

“This is an important milestone in our understanding of proton beam therapy in the UK and abroad, and will help to guide further research in the near future, and hopefully identify ways of making PBT more efficient and effective for cancer therapy,” says Andrzej Kacperek, a consultant proton physicist at the Clatterbridge Cancer Center, currently home to the UK’s only proton therapy beam. The UK government has invested £250 million to open additional centers in Manchester and London by 2020.