A study by the Jacksonville group reported the disease control and toxicity in 12 pediatric patients with multifocal spinal myxopapillary ependymoma (MPE) treated with limited-volume proton therapy. The median age was 13.5 years. Proton radiotherapy was given as adjuvant therapy after primary surgery in five patients (42%) and for recurrence in seven (58%). No patient received prior radiation. Eleven patients (92%) had evidence of gross disease during radiotherapy. Eleven patients received 54 GyRBE; one received 50.4 GyRBE.
With the median follow-up of 3.6 years, the five-year actuarial rates of local control, progression-free survival, and overall survival were 100%, 92%, and 100%, respectively. One patient experienced an out-of-field recurrence in the spine superior to the irradiated region. No patients developed in-field recurrences. Following surgery and irradiation, one patient developed grade three spinal kyphosis, and one patient developed grade 2 unilateral L5 neuropathy.
This study concluded that 54 GyRBE to a limited volume appears effective for disseminated spinal MPE in both the primary and salvage settings, sparing children the toxicity of full craniospinal irradiation. Compared with historical reports, this approach using proton therapy improves the therapeutic ratio, resulting in minimal side effects and high rates of disease control.