Interview with Dr Rémi Dendale, manager of the Proton Therapy Center

What are the advantages of proton therapy?

Rémi Dendale: Thanks to precise ballistics, proton beams have quickly become the tool of choice for radiotherapists. They have the almost unique ability among rays to deliver a uniform irradiation dose at an extremely precise depth. Proton therapy can provide high-precision irradiation to tumors located close to sensitive organs, such as the optic nerve or certain parts of the brain. In addition, it restricts irradiation of healthy tissues and thus limits after effects. As such it is perfectly suited to treating certain tumors in children.

Which patients benefit the most from proton therapy?

In adults, melanoma of the eye was the first tumor to be treated at the center and remains the most common type treated, with 5,000 patients treated so far. Classic therapies are not very effective against this tumor. Of course there is the possibility of surgical enucleation, but proton therapy has the enormous advantage of preserving the eyeball with useful vision in 90% of cases.

The Proton Therapy Center also accommodates around 100 patients each year – adults and children – suffering from chordomas or chondrosarcomas of the base of the skull. These somewhat infrequent tumors are considered to be radio-resistant and require high doses of irradiation. Proton therapy allows the doses received by the tumor to be increased without causing too much damage to neighboring organs.

Children benefit most from proton therapy since it is better at protecting the organs at risk, reducing complications and the risk of secondary tumors. The clinical data, presented in 2008 by the team from the Proton Therapy Center in Boston, which has over 20 years of experience – mainly in adults – confirm a more than 50% reduction in the risk of secondary cancers compared with classic radiotherapy. Now, given the considerable improvement of the overall prognosis for pediatric tumors over the past 30 years, the treatment and prevention of complications and very long-term therapeutic after effects are an overriding goal. More than 490 children have been treated using proton therapy since 2006, of which more than 140 were under general anesthesia.

What does the future hold?

In the spring of 2017, a new milestone was reached with the treatment of the first patient using the pencil beam scanning (PBS) technique. With this new technology, it is now possible to scan the tumor with the proton beam and thus treat tumors with complex volumes. We will be able to extend the indications for tumors that may benefit from proton therapy.

These include children suffering from medulloblastoma, a tumor that develops in the cerebellum. Only children whose tumor base is located in the region of the cerebellum can currently be treated at the Proton Therapy Center. Thanks to PBS, we will be able to offer this treatment to other children for other tumor locations (mediastinum, abdomen, pelvis, etc.).