(P016) Management of Pediatric Intracranial Low-Grade Gliomas: Long-Term Follow-up After Radiation Therapy

Minh-Phuong Huynh-Le, BS, Amanda Walker, MD, George Jallo, MD, Kenneth Cohen, MD, Moody Wharam, MD, Stephanie Terezakis, MD; Johns Hopkins University School of Medicine

Introduction: The treatment of pediatric low-grade gliomas (LGGs) generally begins with maximal safe resection. Radiation therapy (RT) and chemotherapy are typically reserved for patients with incomplete resection and/or disease progression. We report long-term treatment outcomes and toxicities in a cohort of pediatric patients with LGG after RT.

Methods: A retrospective single-institution study was performed for pediatric patients with intracranial LGG. Thirty-three patients aged < 21 years at diagnosis who received RT between 1982 and 2010 were included in this analysis. Patients were evaluated for overall survival (OS) after RT, progression-free survival (PFS) after RT, timing of RT, patterns of failure, and toxicity. Descriptive statistics and the Kaplan-Meier method were used for analysis. A Cox proportional hazards regression analysis was performed to determine which parameters were significant under multivariate analysis.

Results: The mean age at diagnosis was 7.7 years (range: 1.2–18.3 yr), and mean age at time of radiation was 10.7 years (range: 3.0–28.9 yr). The median follow-up time was 9.4 years after radiation (range: 0.8–22.1 yr). Seventeen patients were male (52%). Twenty-five patients (76%) had World Health Organization (WHO) grade I pilocytic astrocytomas, seven (21%) had grade II astrocytomas, and one (3%) had LGG not otherwise specified.

At the time of diagnosis, 2 patients (6%) underwent gross total resection (GTR), 18 (55%) underwent subtotal (STR), 4 (12%) underwent partial resection (PR), and 9 (27%) underwent biopsy alone. Fifteen (45%) patients received chemotherapy.

Chemotherapy regimens varied but included treatment with temozolomide, vincristine, and/or carboplatin. Ten patients (30%) received chemotherapy before RT, three (9%) received concurrent chemoradiation, and two (6%) received chemotherapy after RT.

All patients in the cohort received RT; 18 (55%) received conventional, 9 (27%) received intensity-modulated RT (IMRT), 3 (9%) received 3D-conformal, 2 (6%) received fractionated stereotactic radiotherapy, and 1 (3%) received stereotactic radiosurgery. Patients received a median radiation dose of 53.4 Gy (range: 38.0–55.8 Gy). The patient who received SRS was treated with 15 Gy in a single fraction. Twenty patients (61%) received adjuvant radiation after surgical resection, seven (21%) received radiation after a biopsy, and six (18%) received salvage radiation at time of progression. Estimated 10-year OS and PFS were 91% and 73%, respectively. Eleven patients had disease progression after RT, and all failures were local. The median time to progression was 3.6 years (range: 0.5–16.4 y) after RT. One of the 11 patients who progressed after RT developed malignant transformation to a high-grade glioma 16.4 years after RT. Two patients died due to disease progression 2.3 and 9.1 years after RT, respectively. At last follow-up, all other patients had stable disease. No significant predictors of PFS were identified on univariate or multivariate analysis.

Late effects that were seen were endocrine hormone deficiencies in 15 patients, hearing loss in 4 patients, and special education requirements for 4 patients. One patient developed a grade 1 falx meningioma 22 years after RT.

Conclusion: In this retrospective single-institution series of pediatric LGG patients treated with RT, excellent OS and PFS were attained at long-term follow-up. Our study suggests that the use of radiation is important for tumor control in pediatric LGG, with acceptable toxicity.