Cancers treated: childhood cancers
A high-precision form of radiotherapy, proton therapy reduces the exposure of healthy tissue surrounding the tumor, and thus reduces the toxicity of the rays compared with classic radiotherapy. It is therefore perfectly suited to treating children. “It can provide high-precision irradiation to pediatric tumors located deep inside the body and close to sensitive organs, such as the optic nerve or certain parts of the brain,” explains Dr Sylvie Helfre, a radiotherapist.
“Proton therapy reduces the risk of secondary cancer in young patients,” says Dr Claire Alapetite, also a radiotherapist. “Therefore, as far as possible, we need to offer it to all children for whom it is technically feasible.”
Childhood tumors treated at the Proton Therapy Center
Medulloblastomas are malignant tumors of the posterior fossa region of the brain, occurring mainly between the ages of 3 and 8. Some 60 cases are diagnosed each year. They grow quickly, which means they are more difficult to treat.
Gliomas are tumors of the central nervous system (brain and spinal cord). These include different types of tumor, depending on the nature of the original cells.
Craniopharyngiomas are tumors of the pituitary gland region. They account for 15% of child brain tumors.
Rhabdomyosarcomas are the most common malignant mesenchymal tumors (60% to 70% of all). They develop in the striated muscle cells and are found in 22% to 26% of cases in the head and neck. They are treated with a combination of chemotherapy, surgery and, possibly, local radiotherapy.
Ependymomas account for 8% to 10% of child brain tumors. They are found especially in young children (average age at diagnosis: 5). They may develop at any point of the nervous system from the ependyma.
Neuroblastomas are the most common extracranial solid tumor in young children.
50% of children affected – both girls and boys – are under the age of 2. Neuroblastoma develops to affect the sympathetic nervous system. It mainly affects the abdomen and, more rarely, the chest, neck and lower pelvis.
Millimetric precision and constraints
Proton therapy requires positioning with precision to the nearest millimeter. This is made possible by a robotized table and perfect immobilization using a restraint mask. It takes some 20 minutes to prepare the patient, during which time he/she is restrained by a mask and must remain completely still, which is difficult for very young children (under the age of 4). The use of general anesthesia is therefore the only solution to this immobility problem.
“Over 490 children have been treated using proton therapy since 2006, of which more than 140 were under general anesthesia, or one in four,” comments Dr Rémi Dendale, manager of the Proton Therapy Center.