Main Session
Sep
27
PQA 02 - Pediatric Cancer, Sarcoma and Cutaneous Tumors, Medical Education & Professional Development, and Health Services Research
2376 - Long-Term Outcomes and Toxicities Following Radiotherapy for Progressive Pediatric Low-Grade Gliomas After Systemic Therapy
Presenter(s)
Sanjana Shah, BS - Harvard Medical School, Boston, MI
S. B. Shah1, A. Zapaishchykova2, C. Smith2, R. B. Chopra2, J. Zielke1, L. L. Thompson2, K. Wright3,4, S. N. Chi3,4, K. K. Yeo3,4, P. Bandopadhayay3,4, L. Baird3, K. Fehnel3, H. Elhalawani2,3, T. I. Yock1,2, D. A. Haas-Kogan2,3, B. H. Kann1,5, and K. X. Liu2,3; 1Harvard Medical School, Boston, MA, 2Department of Radiation Oncology, Mass General Brigham, Boston, MA, 3Boston Children's Hospital, Boston, MA, 4Department of Pediatric Oncology, Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Boston, MA, 5Department of Radiation Oncology, Mass General Brigham/Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA
Purpose/Objective(s):
With excellent survival outcomes, treatment paradigms for pediatric low-grade gliomas (pLGGs) have shifted to favor systemic therapy over radiotherapy (RT) in efforts to decrease long-term side effects. There is limited data regarding long-term outcomes for patients receiving RT for progressive pLGGs after systemic therapy. Thus, we characterized long-term outcomes after RT for progressive pLGGs who received prior systemic therapy.
Materials/Methods:
This IRB-approved single institution retrospective study includes patients diagnosed with LGGs from 1989-2022 who received RT for progressive disease after =1 line of systemic therapy. Kaplan-Meier method and log rank tests were used for progression-free survival (PFS) and overall survival (OS). Univariate analyses were conducted using competing-risks survival regression models to examine associations between clinical and treatment characteristics and time to progression with death as a competing risk.
Results:
In this cohort of 28 patients, 13 patients (46.4%) were female, and 13 patients (46.4%) had supratentorial midline tumors. Median age at diagnosis was 5.3 years (IQR 2.2-10.4). Most common histologies were pilocytic astrocytoma/LGG with pilocytic features (N=14) or optic gliomas (N=7). Three patients had NF1. All patients had gross disease prior to RT. Median age at RT start was 9.2 years (IQR 6.3-15.9). Median time to RT from diagnosis was 38.0 months (IQR 17.2-61.5). Median RT dose was 52.2 Gy (range 36-54.8) with 8 patients receiving proton RT (28.6%). Median follow-up time from RT start was 20.6 years (95% CI 3.9-25.1). 10-year PFS and OS were 62.8% and 85.9%, respectively. 20-year PFS and OS were 57.6% and 80.5%, respectively. Two patients died of progressive disease and 3 patients died from causes not directly related to tumor progression: adrenal crisis, complications from seizure, and metastatic malignant peripheral nerve sheath tumor. Of the 8 patients who progressed, 7 were within the prior RT field. Nine patients had grade =3 toxicities (32.1%) which included Moyamoya disease (N=5, 19.7%), hearing loss, and vision loss. On univariate analyses, age at diagnosis [HR = 1.21 (95% CI 1.02-1.44, p = 0.025)], age at RT start [HR = 1.20 (95% CI 1.08-1.32, p = 0.001)], and RT dose < 50.4 Gy [HR= 11.6 (95% CI 3.04-44.35, p < 0.001)] were independently associated with shorter time to progression.
Conclusion:
RT remains effective in improving local control for patients with progressive pLGGs after systemic therapy, but continues to carry risks of long-term side effects, particularly vascular complications. Doses = 50.4 Gy were associated with improved local control. RT can be considered for patients who fail multiple lines of systemic therapy or who require preservation of important neurological functions. Long-term quality of life remains an important consideration when selecting treatment modality.