Proton therapy for treating eye melanoma

Marie Colcombet
01/30/2020
Share
Proton therapy is a conservative treatment that lets us irradiate certain cancerous eye tumors with precision. Institut Curie has unique expertise in this field.
consult ophtalmo

In France, Institut Curie is one of only two institutions able to implement proton therapy for treating uveal melanoma: since it opened in 1991, the Proton therapy center at Orsay has already treated over 7,000 patients with eye cancers. Each year, of the 500 to 600 eye melanomas diagnosed, 70% are treated using proton therapy, which allows us to save the patient's eyeball and partially preserve their sight. Proton therapy is an ultra-precise form of radiotherapy that uses proton beams instead of classic photons. It helps spare the healthy tissues around the tumor, above all those around the brain!

Uveal melanoma tumors are most frequently located near the choroid, this membrane between the retina and the white of the eye, known as the sclera. They are generally treated in three stages. "The first involves establishing a precise diagnosis, and possibly taking a sample for a better biological characterization," explains Dr. Rémi Dendale, manager of the Institut Curie proton therapy center. The second is a surgical procedure to place clips in the eye to be used as markers to irradiate the tumor more precisely." These clips are made from tantalum, a non-ferromagnetic metal, which does not interfere with the performance of MRIs.

The third stage - the treatment itself - then takes place over the course of a week.

The patient is seated on a robotized chair, with a thermo-formed mask covering the face. This equipment is essential in order to completely immobilize the body and the head, and at the same time to be able to move the patient, and therefore his/her eye, with precision of 0.1 mm, to position the tumor exactly opposite the proton beam exiting the particle accelerator. Props are used to hold the eyelids open, but this is not painful since an anesthetizing collyrium is used," explains the physician The first day, medical imaging shots are taken to locate the clips and model the eye and the tumor in 3D, and thus precisely calculate the beam needed to treat it A simulation shot is also taken The tumor will then be irradiated for around 60 seconds, during four treatment sessions over the course of four consecutive days "If the tumor is relatively large, necrosis of the tissues may then cause inflammation, which can damage vision

indicates Dr. Dendale

For some patients, a surgical procedure is therefore needed within two months following the treatment to remove the tumor scar.

Proton therapy is extremely effective: in 95 to 98% of cases it controls the tumor locally, and the risk of recurrence at 10 years is then extremely low, whereas uveal melanoma is a fairly aggressive tumor

In France, Institut Curie is one of only two institutions able to implement proton therapy for treating uveal melanoma: since it opened in 1991, the Proton therapy center at Orsay has already treated over 7,000 patients with eye cancers. Each year, of the 500 to 600 eye melanomas diagnosed, 70% are treated using proton therapy, which allows us to save the patient's eyeball and partially preserve their sight. Proton therapy is an ultra-precise form of radiotherapy that uses proton beams instead of classic photons. It helps spare the healthy tissues around the tumor, above all those around the brain!