International Journal of Radiation Oncology*Biology*Physics
Clinical investigationBrainDistinctive clinical course and pattern of relapse in adolescents with medulloblastoma
Introduction
Medulloblastoma is a highly malignant embryonal central nervous system (CNS) tumor primarily affecting children in the first decade of life. This is the most common malignant brain tumor of childhood, accounting for 20–25% of pediatric CNS neoplasms. Large cooperative and epidemiology studies have contributed to better-defined risk groups and improved treatment modalities and outcomes (1, 2, 3, 4, 5, 6). The pattern of relapse in childhood medulloblastoma has been extensively described (6, 7, 8). Being an embryonal tumor, medulloblastoma is rare in older people and represents <1% of CNS tumors in adults (9). Nevertheless, over the last decade, several retrospective institutional or multicenter studies have described the characteristics, response to treatment, prognosis, and pattern of relapse in adult medulloblastoma (10, 11, 12, 13, 14). Some aspects of adult medulloblastoma differ markedly from what is observed in younger children. For example, conventional pediatric risk groups might not apply to adult patients. The prognosis for these adult patients seems to be favorable, but late relapses are more common. Recently, cancer in adolescents has been identified as an important entity because adolescents constitute a significant and unique group with regard to treatment and prognosis. In most pediatric medulloblastoma series, mean age at diagnosis is 6–8 years (1, 2, 4, 5, 6). Furthermore, adolescents were never evaluated separately, indicating that most available data might not apply to this group. Moreover, up to 27% of medulloblastoma patients are >10 years of age at diagnosis (15), making them a neglected but considerable group of patients. The discrepancy between the findings in adult and pediatric studies mandates a closer look at patients in transition from childhood into adulthood.
Our aim was to report the clinical course of patients with medulloblastoma aged 10–20 years at diagnosis, with specific emphasis on prognosis and pattern of relapse.
Section snippets
Patients
We performed a multicenter retrospective study that included 10 centers participating in the Canadian Pediatric Brain Tumor Consortium (CPBTC). The CPBTC is a group of tertiary care Canadian centers involved in the development and conduct of studies related to pediatric brain tumors. We reviewed the charts of patients aged ≥10 years and ≤20 years at diagnosis, who were defined as teenagers, treated at these centers between 1986 and 2003 with a diagnosis of medulloblastoma. This study was
Study population and treatment approach
Data were available for 77 adolescents from 10 pediatric cancer centers of the CPBTC. Five patients were excluded owing to insufficient data, thus 72 adolescents were included in this study. Demographic, clinical, and treatment characteristics are listed in Table 1. Craniospinal irradiation with a boost of 51–55 Gy to the tumor bed was given to all patients, including the younger controls. All but 1 patient from the high-risk group received ≥35 Gy to the craniospinal axis. Of the 45 patients in
Discussion
The aim of this multicenter, retrospective study was to describe the survival characteristics and the pattern of relapse in adolescents with medulloblastoma. Our findings support the growing hypothesis that adolescents with cancer are distinct from younger children and constitute a separate group. In our experience, OS and EFS at 5 and 8 years revealed a pattern that seems different from previous reports in younger patients (Table 2). Although the 5-year pattern compared favorably with most
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