PV QA 3 - Poster Viewing Q&A 3
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
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.
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.
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).
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.