Helium Ions May Provide Better-Targeted Treatment in Pediatric Radiotherapy

Scientists have for the first time been able to demonstrate that the use of helium ions in radiotherapy could deliver effective treatment to tumors while sparing healthy organs.

The treatment planning study’s findings were presented at the European Society of radiotherapy & Oncology (ESTRO) 33 Congress, held April 4–8, 2014, in Vienna (Austria), has been able to show that helium may have effects that are superior to radiotherapy using protons, which is a considerable advance on traditional photon beam radiotherapy.

Hermann Fuchs, a PhD student at the Medical University of Vienna/AKH (Austria), working with Dr. Barbara Knäusl and Prof. Dietmar Georg, set out to devise a way of calculating the optimal dose of helium ions for use in radiation treatment. The dose calculation algorithm was then used for treatment plan calculation for 10 pediatric patients, five with neuroblastoma (tumors arising in cells of the hormonal and nervous system), and five with Hodgkin’s lymphoma (a cancer of the white blood cells).

“Particle beam therapy involving protons or carbon ions has advantages over conventional radiotherapy. Helium ions may represent another kind of particle that can improve radiotherapy treatment. Due to their increased mass, spreading of the beam is reduced by a factor of two as compared with protons. Moreover helium ions have an increased biological effectiveness at the end of their range,” Mr. Fuchs explained.

Heavier ions such as carbon have the potential to kill cancer cells more effectively due to their underlying biology. But by modelling these biologic processes, a number of unknowns are introduced, and these can be reduced by using lighter ions such as helium. “Helium ions reside in the low linear energy transfer [LET] area,” said Mr. Fuchs. “LET is a physical quantity describing how much energy of a particle is deposited at a given range, and this measure is important when looking at the biological effects of therapy.”

This greater accuracy and sparing of healthy tissue is essential in the case of children, the researchers reported. When treating them it is especially important to ensure that as little dose of radiation as possible is placed outside the area to be treated, because an increased area treated with a low dose can lead to the development of secondary tumors. Given that children have a potentially long lifespan ahead of them, this probability needs to be reduced as much as possible through the use of therapies that are targeted as precisely as possible to the tumor, while sparing the dose to neighboring areas, and especially to healthy organs particularly sensitive to radiation located nearby (the organs at risk).

“After three years of extensive research and validation efforts, we were able to produce a treatment planning algorithm that enabled us to investigate the possibilities for using helium ion therapy in children treated with low dose radiation. We would now like to investigate its potential in patients being treated with higher doses, for example, those with brain tumors. The good results that have been achieved so far warrant the verification of the model in order to investigate the real clinical potential of helium ions,” Mr. Fuchs said. “In the long term, clinical trials of this therapy will be needed to substantiate the effects of our treatment planning model. “Particle beam therapy has already advanced care and treatment options for cancer patients. We hope that the use of helium ions may help to bring about further improvements.”

President of ESTRO, Prof. Vincenzo Valentini, a radiation oncologist at the Policlinico Universitario A. Gemelli (Rome, Italy), commented, “This is an exciting study that holds out hope for improved, more accurate radiation treatment for young cancer patients.”

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Medical University of Vienna/AKH