Proceedings of the 49th Annual ASTRO Meeting S579

2680 Improved Hearing Outcomes From Cochlear Dose Reduction Using Proton Posterior Fossa Boost in

Pediatric Medulloblastoma

Y. Chen, J. Adams, T. Yock, B. Esty, B. Fullerton, N. J. Tarbell

Massachusetts General Hospital, Boston, MA

Purpose/Objective(s): Ototoxicity remains a significant late toxicity after craniospinal (CSI) and posterior fossa (PF) irradiation aswell as platinum-based chemotherapy for pediatric medulloblastoma. To investigate whether the use of protons for posterior fossaboost might result in decreased ototoxicity by minimizing cochlear dose, we performed a retrospective review of a group ofmedulloblastoma patients treated with photon CSI and proton posterior fossa boost.

Materials/Methods: Of the 25 children with medulloblastoma treated at the Harvard Cyclotron and the Francis H. Burr ProtonTherapy Center between 1997 and 2002, patients with standard risk medulloblastoma who received 23.4 Gy photon CSI followedby 30.6 GyE (Gy equivalent) of proton boost to the whole posterior fossa were reviewed. Patients who received involved field onlyor proton CSI and PF boost were not included. Dose volume histograms of right and left cochlea were calculated. All patients wenton to platinum based maintenance chemotherapy after radiation. Audiograms and clinical records were reviewed to determine hear-ing outcomes.

Results: Twelve children with standard risk medulloblastoma underwent photon CSI and proton PF boost. Comparison of protonand conventional photon plans of the PF boost found substantial cochlear dose reduction with proton PF boost. The average meancochlear dose using protons was 30.8 ± 2.5 Gy (57% of total dose) compared with 100% with photons. Photons contributed anaverage of 71% of cochlear dose and protons contributed an average of 29% of the cochlear dose. At a median follow-up of4.67 months, two of the 12 patients relapsed with leptomeningeal disease. Of the 10 patients without evidence of disease, threepatients were lost to follow-up. Seven patients who have audiograms at least one year after treatment completion (median of 4years) and have clinical follow-up were analyzed. Six of the seven patients developed 10 to 70 dB high frequency sensorineuralloss in the 4000 to 8000 Hz high frequency range, while one patients developed 25 dB loss in the speech range of 2000 Hz as well as85 dB loss in the high frequency range. Mean speech discrimination score was 96% (range 84 to 100%). All patients had the firsthearing loss detected during chemotherapy. In 6 patients, hearing changes persisted at the same level after completion of all treat-ments and at last follow-up; however, one patient had a 20 dB improvement in the high frequency range two years after completingtreatment. Audiologists recommended preferential seating and FM amplifiers in school for two patients. One patient was recom-mended occupational noise reduction. None of these seven patients required the use of a hearing aid.

Conclusions: Proton radiation to the posterior fossa significantly reduces cochlear dose in pediatric medulloblastoma. While mostpatients experienced some degree of sensorineural loss during platinum-based maintenance chemotherapy, few required long-termintervention and none required a hearing aid. The hearing outcomes of these patients are superior compared to rates observed afterconventional photon CSI and posterior fossa irradiation in the literature.

Author Disclosure: Y. Chen, None; J. Adams, None; T. Yock, None; B. Esty, None; B. Fullerton, None; N.J. Tarbell, None.

2681 Radiation Is an Important Component of Multimodality Therapy for Pediatric Supratentorial

Neuroectodermal Tumors

S. M. Daganzo, A. Banerjee, N. Gupta, K. R. Lamborn, M. D. Prados, M. S. Berger, W. M. Wara, D. A. Haas-Kogan

University of California–San Francisco, San Francisco, CA

Purpose/Objective(s): Supratentorial primitive neuroectodermal tumors (sPNET) are more aggressive than their more commoninfratentorial counterparts. Standard of care includes surgical resection, chemotherapy (CT) and craniospinal radiotherapy (CSRT).In this retrospective review, we sought to clarify the role of radiation in the treatment of pediatric sPNETs.

Materials/Methods: Nineteen children\18 years old with non-pineal sPNETs diagnosed between December 1992 and December2006 were identified. Four patients without adequate follow-up (FU) were excluded, leaving 15 evaluable patients. The median ageat diagnosis was 3.1 years (range 0.2–12) and 33% were males. Initial therapy consisted of surgery and CT in all patients and RT in5 patients. The most common CT regimen included cisplatin, etoposide, cyclophosphamide, and vincristine; 2 patients receivedhigh-dose CT with autologous stem cell rescue.

Results: Median FU from diagnosis was 31 months (range 0.5–161) for all patients and 50 months (range 8–161) for survivingpatients. For the entire cohort, median overall survival is 31 months (range 0.5–161). Five children died of their disease 0.5–31months from diagnosis (median 4 months). Ten children are alive and NED for periods ranging from 8–161 months after diagnosis.Five patients received RT as part of their initial treatment (one was\3 years old at diagnosis) and none have progressed (FU range28–161 months). Ten patients did not receive RT as part of their initial therapy (6 were \3 years old at diagnosis) and 8 of thesechildren progressed with median time-to-progression of 6 months (range 1–26). Of the 8 children who progressed, 3 of 5 who re-ceived RT as part of salvage therapy are NED 24, 89, and 95 months after first progression. Of the 3 patients who progressed but didnot receive RT as part of salvage treatment, all died of disease 0.5, 1, and 2 months after progression. In examining the RT fieldsutilized in the 10 patients who received RT (5 at diagnosis and 5 at progression), 5 had CSRT and 5 had focal field only. Of the 5patients who received CSRT, none of the 4 who received it initially progressed whereas the patient who received it as salvage ther-apy died of his disease. Of the 5 patients whose RT consisted of focal field only, 4 are NED for periods ranging from 33–115 monthsafter diagnosis while 1 died of her disease 31 months after diagnosis. Within our cohort of 15 patients, 13 were M0 and 2 were M+at diagnosis. Of the M0 patients, patterns of failure for the 6 that recurred were local only in 3 patients and local plus leptomeningealdissemination in 3 patients. Our cohort included 7 patients\3 years at diagnosis and 5 of these young children are alive and NED atlast FU (range 27–115 months after diagnosis). Four of these 5 patients received RT as part of their treatment, all consisting of focalfield only (1 at initial therapy and 3 as salvage).

Conclusions: Radiation plays an important role in the multimodality treatment of sPNETs. Promising results are evident whenradiation consists of focal field only. Children \3 years old faired well following multimodality therapy that included focal fieldradiation. Local recurrence was a component of failure in every patient who relapsed.

Author Disclosure: S.M. Daganzo, None; A. Banerjee, None; N. Gupta, None; K.R. Lamborn, None; M.D. Prados, None;M.S. Berger, None; W.M. Wara, None; D.A. Haas-Kogan, None.