ENLIGHT++ extends cancer therapy research network

Many concepts and developments from particle physics find applications in health care. High-performance detectors, accelerators and beam technologies are essential for particle physicists to complete their quests. These developments also benefit society by providing better diagnostic tools and tailored radiation treatment of cancer and other diseases. One of the most promising fields in this respect is hadron therapy.

On 24 March more than 100 scientists – including clinicians, oncologists, physicists, radiobiologists, information and communication technology experts and engineers – from about 20 European countries arrived at CERN for the preparatory meeting of the second European Network for Research in Light-Ion Hadron Therapy (ENLIGHT++). This one-day workshop aimed at coordinating European efforts using light-ion beams for cancer therapy. The two plus signs in ENLIGHT++ refer to more countries and more hadrons (specifically protons), and emphasize these extensions to the previous project, which carried the same name (see CERN Courier October 2005 p31).

ENLIGHT, which had its inaugural meeting at CERN in February 2002, was established to coordinate a pan-European effort with a common multidisciplinary platform for using light-ion beams for radiation therapy. It has been instrumental in promoting the advantages of using hadrons, particularly carbon ions. A collaboration of scientists from various European centres and institutions formed the original network, which the European Commission funded for three years. In these centres resides the core expertise in the physics and engineering of accelerators and detectors, which can be used towards the design, advancement and realization of new hadron-therapy machines and other equipment to benefit health.

The importance of hadrons

There are many instances of tumours located near critical organs for which conventional radiation therapy with X-rays is inappropriate. In these cases successful tumour control often means that the dose delivered must reach such a high level that it can damage the surrounding critical organs. For this reason, hadrons – protons or light ions – are more appropriate for radiotherapy of deep-seated tumours. These particles penetrate the patient with practically no diffusion and can easily be formed into narrow “pencil” beams; most importantly, they have a well-defined variable penetration depth, delivering most of their dose at the end of their range in matter. Because of these properties, hadron beams allow highly conformal treatment that follows the shape of the deep-seated tumours with millimetre accuracy, while delivering only very small doses in the surrounding area, hence sparing the healthy tissues.

The idea of hadron therapy dates back to 1946, when Robert Wilson, physicist and founder of Fermilab, was the first to propose using hadrons for cancer treatment; almost 10 years later, 30 patients were treated with protons at the Lawrence Berkeley Laboratory (LBL). In the late 1960s, pioneering studies were carried out at CERN and, in the early 1990s, Ugo Amaldi at CERN vigorously promoted the development of new proton-ion accelerators. In 1999, CERN, the Gesellschaft für Schwerionenforschung (GSI) in Germany, Med-Austron in Austria, Onkologie 2000 in the Czech Republic and the Terapia con Radiazioni Adroniche (TERA) foundation in Italy realized the Proton-Ion Medical Machine Study (PIMMS) to design an ion synchrotron that is optimized for medical applications (CERN Courier September 1998 p20).

The success of therapy projects at nuclear-research centres, along with improved accelerator technology, dose delivery systems and dose calculations, has led to a number of dedicated proton-therapy facilities. These include the Loma Linda University Medical Center in California and the Northeast Proton Therapy Center in Massachusetts in the US, and the Kashiwa and Tsukuba centres in Japan. Proton-therapy facilities also exist in France, Germany, Italy, Russia, Sweden, Switzerland and the UK. In Switzerland, at the Paul Scherrer Institute (PSI), Europe’s leading centre for treating deep-seated tumours with scanned proton beams, a new superconductive cyclotron has been built exclusively for proton therapy and related research. Since Wilson’s initial proposal, about 45,000 patients have been treated with protons with excellent results for head and neck tumours.

Treatment of deep-seated tumours with light ions is less well established and it is this area that the ENLIGHT network targeted. About 10 years ago, radiobiologists and radiotherapists concluded that the optimal ions for therapy are found in the mass range between lithium and carbon. This was based on the results of the treatment of about 2000 patients in the US with helium ions between 1957 and 1987, and of about 400 patients with neon ions from 1975 until 1993, when LBL’s accelerator was closed down.

Since then, clinical results have come from the Japanese Heavy-Ion Medical Accelerator Centre in Chiba and the GSI facility in Germany, where sophisticated raster scanning techniques, in conjunction with online real-time imaging by positron-emission tomography, are used for treatment with carbon-ion beams. The results obtained at these facilities agree with theoretical expectations, thus demonstrating that carbon-ion therapy is an important avenue to follow. Epidemiological data indicate that in Europe about 30,000 patients each year – affected by certain types of cancers, such as those of the pancreas, the saliva-producing parotid gland, uveal melanomas, chordomas and chondrosarcomas of the skull base – would benefit from treatment with ion beams.

The importance of ENLIGHT++

Jos Engelen, CERN’s chief scientific officer, opened the ENLIGHT++ preparatory meeting. He noted that it was appropriate that the workshop took place at CERN as the laboratory has a task in stimulating the application of its technologies, for example, in hadron therapy. CERN has extensive knowledge and expertise in accelerators and related technologies, and indeed hosted and coordinated the PIMMS project.

Following Engelen’s welcome, keynote presentations began with Jean-Pierre Gérard, director-general of Centre Antoine-Lacassagne and past chair of the European Society for Therapeutic Radiology and Oncology, who illustrated the compelling reasons why ion therapy is essential. He pointed out that ENLIGHT++ is a new step that should bring the use of carbon ions into an era of clinical reality.

Ugo Amaldi from the Università di Milano Bicocca and the TERA Foundation – who has promoted hadron therapy for many years – later underlined that, since the beginning of the previous ENLIGHT initiative, the Heidelberger Ionenstrahlen-Therapie facility in Germany and the Centro Nazionale di Adroterapia Oncologica in Italy have begun construction, while Med-Austron in Austria and the European Light Ion Oncological Treatment Centre in France have been approved. (Since the meeting, it has been announced that another facility for hadron therapy will be built in Germany. Hosted by the Marburg-Giessen Klinikum, it will use carbon ions and protons and will be functional in four years.)

Amaldi continued by adding that the hadron-therapy community needs to put in place two kinds of collaboration: the first to develop a common view on issues such as authorization protocols and patient selection, and the second, crucial for ENLIGHT++, to provide Ramp;D involving European groups as a follow-up of ENLIGHT activities and new research initiatives. The community should identify and define the key areas in which further work is needed and obtain funding from the European Commission to carry out the necessary research.

Following the introductory talks, the participants split up into working groups to discuss such an aim. The groups then reported back and the meeting agreed that studies on clinical trials, radiobiology focused on treatment therapy, modalities to improve the delivery of the radiation dose, novel designs of detectors and equipment, and information sharing should all be pursued with the highest priority. Lastly, Manjit Dosanjh was chosen as official coordinator for the ENLIGHT++ initiative.

In summary, the main objective for ENLIGHT++ is to form a consensus from representatives of different disciplines and national programmes in a way that most benefits the patient. It is now agreed that this goal can be met by reinforcing the existing pan-European network, focusing on the areas of research needed for effective hadron-therapy centres, and establishing and implementing common protocols for treating patients.

Further reading

For more information see www.cern.ch/enlight.