Pediatric Cancer

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TU_24_3106 - Short Hypofractionated Radiation Therapy in Palliation of Pediatric Malignancies: Outcomes and Toxicities

Tuesday, October 23
1:00 PM - 2:30 PM
Location: Innovation Hub, Exhibit Hall 3

Short Hypofractionated Radiation Therapy in Palliation of Pediatric Malignancies: Outcomes and Toxicities
S. Lazarev1, B. Kushner2, and S. L. Wolden2; 1Icahn School of Medicine at Mount Sinai Department of Radiation Oncology, New York, NY, 2Memorial Sloan Kettering Cancer Center, New York, NY

Purpose/Objective(s): Treatment strategies in palliation of pediatric cancer are not well-defined and remain a significant challenge. While surgery is often associated with significant morbidity and extended recovery time, systemic therapy and prolonged courses of radiation can lead to an increased hospital/clinic time. In this context, palliative measures aimed at delivering treatment within a short period of time with minimal toxicity should be prioritized. In this study, we aimed to assess efficacy and safety of a short course (≤5 fractions) of hypofractionated RT for metastatic, or recurrent pediatric malignancies.

Materials/Methods: A total of 104 lesions in 62 patients aged ≤18 years with metastatic or recurrent disease were treated with a short hypofractionated RT (>1 but ≤5 fractions; ≥3 Gy per fraction) in the period of 2007-2017 in our institution. Primary endpoint of the study was local control (LC). Other endpoints included treatment response, overall survival (OS), progression-free survival (PFS), and toxicity. Actuarial LC and survival were examined using Kaplan-Meier and log-rank analyses. Toxicities were assessed using the Common Terminology Criteria for Adverse Events v.4.0.

Results: The most common histologies of the irradiated lesions were neuroblastoma – 50 (48.1%), osteosarcoma – 17 (16.4%), and Ewing sarcoma – 13 (12.5%). The majority of tumors were metastatic - 91 (87.5%). A median total dose of 24 Gy (range, 15-40 Gy) was delivered to the analyzed sites in a median of 5 fractions (range, 3-5). 26 lesions (25.0%) were treated with SBRT, 24 (23.1%) – IMRT, 48 (46.2%) –2D or 3D-CRT. A total of 46 (74.2%) patients received systemic therapy after completion of RT. Complete/partial response (C/PR) was observed in 63 (60.6%) lesions, stable disease (SD) - in 34 (32.7%), and progression – in 7 (6.7%). At a median follow-up of 8.7 months, there were 21 (20.2%) local failures out of 104 irradiated tumors. The LC rates at 1 and 2 years were 74% and 68%, respectively. LC was better for tumors with C/PR 86% vs 68% with SD (p<0.00001) and for tumors that had not been previously irradiated 83% vs 57% with prior RT (p=0.004). LC rates did not differ between RT techniques, or total BED10 (≤30 Gy vs >30 Gy). There was a trend toward improved LC with irradiation of bony vs non-bony sites, 81% vs 62% (p=0.09). At the time of analysis, 38 (61.3%) deaths were recorded. The 1-year PFS and OS rates were 31% and 44%, respectively. The incidence of any grade ≥3 toxicity was 6.7% (7 of 104), most of which (n=5) were grade 3. There were no grade 5 toxicities. Three of 7 toxicities were acute (≤ 60 days).

Conclusion: To the best of our knowledge, this is the largest to-date analysis of outcomes with short hypo-fractionated RT in palliation of pediatric malignancies. Short regimen of radiation (≤5 fractions) yields effective local control and excellent treatment response with very favorable side effect profile. Select pediatric patients with symptomatic metastases or recurrent disease can be considered for a short palliative course of RT.

Author Disclosure: S. Lazarev: None. S.L. Wolden: None.

Stanislav Lazarev, MD

Mount Sinai Health System

Biography:
I am currently a Chief Resident in Radiation Oncology at Mount Sinai Hospital in New York, NY. My research interests lie in the field of head and neck malignancies, pediatric tumors, LDR-brachytherapy for prostate cancer, and SBRT for hepatocellular carcinoma. My clinical interests are broad, and include treatment of pediatric malignancies, gynecologic, head and neck, and gastrointestinal cancers.

I grew up in the south of Russia where I studied foreign languages at a linguistic university. At the age of 21, I moved to California where in 2009 I graduated from UC Berkeley with a BA in biochemistry and molecular biology. I received my medical degree at University of Vermont College of Medicine in 2014, and then returned to the Bay Area to complete a medicine internship at Highland Hospital in Oakland. In 2015 I joined the Radiation Oncology Residency Program at Mount Sinai. Outside of medicine, I enjoy learning foreign languages, playing the piano, traveling abroad, and playing soccer.

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