Pediatric Cancer

PD 04 - Pediatrics 1 - Poster Discussion

1031 - Early Outcomes and Patterns of Relapse in Neuroblastoma Patients Treated with Scattered and Proton Beam Scanning Techniques

Sunday, October 21
5:09 PM - 5:15 PM
Location: Room 217 C/D

Early Outcomes and Patterns of Relapse in Neuroblastoma Patients Treated with Scattered and Proton Beam Scanning Techniques
M. Ioakeim-Ioannidou1, J. A. Hattangadi-Gluth2, C. B. Hess1, T. I. Yock1, and S. MacDonald1; 1Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA, 2University of California, San Diego, La Jolla, CA

Purpose/Objective(s): To report early outcomes and patterns of relapse for children with high- or intermediate-risk neuroblastoma treated with proton radiation therapy including scattered and proton beam scanning techniques.

Materials/Methods: We performed a mixed prospective/retrospective study of patients with neuroblastoma treated with scattered/conformal or pencil beam scanning proton therapy at our institution between 2005-2017.

Results: Twenty-four patients were treated with proton therapy, 21 with conformal protons and 3 with pencil beam scanning. Twelve were enrolled on a prospective trial. Median age at diagnosis was 2.75 years (10 months-18 years). All patients had International Neuroblastoma Risk Groups Staging System [INRGSS] stage L1 (n=1), L2 (n=3) or M (n=20) at diagnosis. Nineteen patients had stage IV high-risk disease, 3 patients had stage III high-risk disease, 1 patient had stage IV intermediate-risk disease, and 1 patient had stage IIB intermediate-risk disease. Twenty-one patients were treated for primary disease; 2 intermediate-risk patients were treated for progression of disease and 1 high-risk patient relapsed before the delivery of RT and he was treated for progressive disease. All patients had unfavorable histological characteristics [poorly differentiated histology (n=21), N-Myc amplification (n=12), 1p/11q chromosomal abnormalities (n=8), bone marrow involvement at the time of diagnosis (n=15). Median tumor size at the time of diagnosis was 9.5 cm (range 2.9-16.2 cm) in maximal dimension and mainly abdominal (n=5) or retroperitoneal (n=14). Patients received induction (n=21) or post-op (n=3) chemotherapy, surgical resection of their tumor(n=22), high-dose chemotherapy followed by one (n=17) or two (n=7) stem cell rescue transplantations, and adjuvant RT to primary tumor sites +/- selective sites of metastatic disease. At a median post-RT follow-up of 32 months (1-113 months), there was no local failure. No patient failed inside the radiation field. Eight patients relapsed after RT locoregionally (n=1) or distantly (n=7), and of these, six died of disease. None of the three patients treated with PBS experienced recurrence. Five patients experienced acute grade ≥2 side effects: four with grade 2 anorexia and one patient with grade 2 pneumonitis which resolved after initiation of steroids.

Conclusion: Preliminary outcomes show favorable local control with proton beam irradiation for high-and intermediate-risk neuroblastoma. Similar to the photon experience, distal recurrence continues to be the predominant pattern of relapse. These data represent the largest series of neuroblastoma patients treated with proton radiation therapy.

Author Disclosure: M. Ioakeim-Ioannidou: None. J.A. Hattangadi-Gluth: Research Grant; Varian Medical Systems. C.B. Hess: None. T.I. Yock: Research Grant; IBA, Protom, Elekta. Advisory Board Member; Ronald McDonald House Charities. S. MacDonald: None.

Myrsini Ioakeim-Ioannidou, Medical Student

Disclosure:
No relationships to disclose.

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