Australian approach enhances particle therapy for cancer treatment

A new addition to charged particle therapy cancer treatment developed by the Australian Nuclear Science and Technology Organisation has been shown to enhance its efficacy in cell studies.

The Neutron Capture Enhanced Particle Therapy (NCEPT), could be used to effectively target deep cancer tumours, and those which are more diffuse.

A new study reports  that human glioblastoma cells treated with neutron capture agents showed delayed growth and 3-5 times greater reduction in survival when irradiated with carbon and helium ion beams, compared to ion radiation alone.

The research has been published in the International Journal of Radiation Oncology, Biology, Physics.

“Our results show the potential for NCEPT to provide an increased dose to tumour tissue while reducing radiation doses to off-target tissue,” says Dr Mitra Safavi-Naeini, a senior physicist at Australian Nuclear Science and Technology Organisation (ANSTO) who led the project.

“This could lead to better outcomes for patients with challenging cancers, such as brain tumours, that are difficult to treat with conventional therapies.”

Particle therapy uses streams of energetic neutrons, protons or heavier positively charged ions to bombard cancerous tumours. These particles damage the DNA of the cells, ultimately causing their death. Cancer cells are particularly vulnerable to particle therapy because they have reduced ability to repair DNA.

However, a fraction of these particles may collide with atomic nuclei inside the target area. This causes the atoms to fragment, sending out thermal neutrons which irradiate both cancerous and non-cancerous tissues indiscriminately.

But NCEPT enhances the effectiveness of particle therapy by delivering a tumour-targeting neutron capture agent to cancer cells, which reduces radiation doses to non-cancerous tissue.

A graphic showing the steps of neutron capture enhanced particle therapy. In step 1 tumour cells are treated with targeted neutron capture agents. In step 2 a particle beam collides with atoms in the target area producing fragmentation products including thermal neutrons. In step 3 thermal neutrons are captured by the neutron capturing agents in the cells. In stem 4 electrons, lithium, and alpha particles resulting from the neutron capture create dna double-strand breaks, predominantly killing cancer cells.
Physics of neutron capture enhanced particle therapy. Credit: International Journal of Radiation Oncology, Biology, Physics

The team believes there is potential for NCEPT to be applied to a wider range of deeply situated and diffuse tumours.

“We believe that NCEPT represents a new paradigm in charged particle therapy,” says first author Nicholas Howell, a radiation biologist at ANSTO.

The team is now planning further research to evaluate the efficacy of NCEPT in vivo and to explore its potential for clinical translation. 

Particle therapy is not yet available in Australia, but the Australian Bragg Centre for Proton Therapy and Research in Adelaide is under construction and expected to commence operations in 2024-25.

The Queensland Government is also funding the establishment of a new Cancer Centre in Brisbane to deliver proton therapy.

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