High-dose proton RT offers excellent chances of lasting tumor control and survival, with acceptable risks. In this series all small- and medium-sized tumors with no demonstrable brainstem involvement have been controlled; all such patients are alive. Surgical debulking enhanced delivery of full tumoricidal doses, but even patients with large tumors and disease abutting crucial normal structures benefited.

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This report on pediatric low-grade astrocytomas confirms proton radiation therapy as a safe and efficacious 3-D conformal treatment modality. Results are encouraging for central tumors as well as large optic pathway tumors, where dose conformity is of particular importance; yet it is difficult to achieve. Longer follow-up time is needed to fully evaluate the benefits of normal tissue sparing.

Purpose: This prospective cohort evaluated patients with acoustic neuroma treated with proton irradiation at Loma Linda University Medical Center. A dose of 50.4 Gy in 28 fractions was given to improve hearing preservation while maintaining tumor control. Patients and Methods: Ninety-five patients were treated from March 1991 to March 2008. Fractionated proton radiotherapy at daily doses of 1.8 Gy was employed. Patients were treated to 1 of 3 total doses: 59.4 Gy, used initially for patients without serviceable hearing; 54 Gy, used for patients with serviceable hearing through October 2000; and 50.4 Gy used since 2001 for patients with serviceable hearing. Survival and local control were calculated using the Kaplan-Meier method. Logistic regression analysis was preformed comparing dose, tumor size, and tumor location with hearing preservation. Results: Ninety-four patients were assessable; the median follow-up was 64 months.Five-year local control rates for the 59.4 Gy, 54 Gy, and 50.4 Gy groups were 95%, 97%, and 92%, respectively (P ¼ .80); the overall 10-year actuarial control rate was 90%. Cranial nerve injuries occurred in ,5% in all groups. Four-year actuarial rates of hearing preservation were maintained in 44% of patients treated with 54 Gy and 64% treated with 50.4 Gy (P ¼ .284). On multivariate analysis, initial tumor diameter (1.5 cm) was found to be a prognostic factor for maintaining serviceable hearing in both groups (P ¼ .011). Conclusions: Fractionated proton therapy of 50.4 Gy offers excellent local control and minimal cranial nerve toxicities. Improved rates of hearing preservation that are comparable with radiosurgery were seen with 50.4 Gy compared with higher doses, although this did not reach significance. Maintaining hearing was found to be associated with smaller initial tumor size.

Our proton-beam technique for craniospinal irradiation of pediatric medulloblastoma has successfully reduced normal-tissue doses and acute treatment-related sequelae. This technique may be especially advantageous in children with a history of myelosuppression, who might not other wise tolerate irradiation.