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Treatment outcome of pediatric brain tumor under the age of 3 treated by intensity-modulated radiotherapy

Other Titles
 세기 조절 방사선 치료를 받은 3세 미만 소아 뇌암에서의 치료 결과 연구 
 College of Medicine (의과대학) 
 Dept. of Radiation Oncology (방사선종양학교실) 
Issue Date
Purpose: Central nervous system (CNS) tumors are the second most common cancers in children, and the most common cause of death among all childhood cancers. Although radiotherapy (RT) is imperative in the management of pediatric CNS tumors, radiation exposure to healthy tissues may lead to neurologic morbidity, which can seriously affect the patient’s quality of life. However, the need for adjuvant RT is emerging in patients below 3 years of age with CNS tumors. Nowadays, intensity-modulated radiotherapy (IMRT) allows for a sharp dose falloff, producing a rapid dose gradient along planning target volume (PTV). This makes it possible to distribute the PTV dose more homogeneously and to deliver lower doses to critical organs. In this background, we investigated the safety and feasibility of IMRT for pediatric CNS tumor patients below 3 years of age. Materials and Methods: A total of 18 pediatric CNS tumor patients below 3 years of age, who received local RT by IMRT between October 2011 and August 2016 were included in the analysis. In surgery, 6 patients, 4 patients, 5 patients, and 2 patients received gross total resection, near total resection, subtotal resection, and partial resection, respectively. Ten patients received chemotherapy, of which 9 patients received peripheral blood stem cell transplantation. Regarding RT, the median total dose was equivalent to a dose of 2 Gy fractions (EQD2) 52.6 Gy (range, 34.6–60 Gy, α/β=3). Median age was 21.0 months (range, 10.7–33.0 months). The median size of the tumor at initial diagnosis was 4.9 cm (range, 1.7–10.0 cm), and half of all the tumors were located in the infratentorial region. The most common pathology was anaplastic ependymoma (38.9%), followed by atypical teratoid/rhabdoid tumor (AT/RT) (22.2%). Treatment outcomes and neurologic morbidities were retrospectively reviewed in detail. Results: Patients with anaplastic ependymoma had 5-year overall survival (OS) and 5-year freedom from local recurrence (FFLR) of 50.0% and 38.1%, respectively. Five of the 7 anaplastic ependymoma patients recurred; 3 patients had local recurrence, 1 patient had local recurrence and craniospinal fluid (CSF) seeding, and the other 1 patient had CSF seeding alone. For AT/RT patients, 5-year OS and FFLR were both 100.0%. There was one recurrence in AT/RT patients; the location of the recurrence was in the intracranial area, but outside the RT field. It was successfully salvaged with focal radiation. Among 7 patients of remaining pathologies, the 5-year OS and FFLR were 71.4% and 100.0%, respectively. Two patients died due to infection. Regarding morbidity, 4 patients showed combined neurocognitive and motor dysfunction, 3 patients showed motor dysfunction and 1 patient showed hearing impairment. Except for 1 patient with a hearing impairment only, 7 patients had tumors located around the 3rd or 4th ventricle. Due to the location of the tumor, hydrocephalus was associated with these 7 patients from the time of diagnosis. Investigations into the time of onset of neurologic morbidities and the time of RT showed that 6 of 8 patients already had a neurologic deficit before RT. One of the patients with hearing loss in the other 2 of the 8 patients had a hearing test only after RT. Taken together, results suggest that neurologic morbidity is unlikely to be caused by RT alone, and is rather thought to occur due to a combination of mass effects from the tumor itself and sequelae from surgery and chemotherapy. Conclusion: Administration of IMRT to patients below 3 years of age showed encouraging local control rates and tolerable morbidities. High-precision modern RT such as IMRT should be considered for very young patients with high-risk CNS tumors.
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1. College of Medicine (의과대학) > Dept. of Radiation Oncology (방사선종양학교실) > 2. Thesis
Yonsei Authors
Lee, Joongyo(이준교)
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