Treatment Outcome and Prognostic Factors for Pediatric Medulloblastoma Patients: The Egyptian National Cancer Institute Experience

Abstract

Purpose: To evaluate treatment outcomes and prognostic factors of pediatric Medulloblastoma (MB) patients treated by adjuvant post-operative riskadapted radiotherapy (RT) and chemotherapy (CT). Patients and Methods: A retrospective analysis was conducted based on medical records of pediatric patients with pathologically confirmed MB treated between 2006 and 2013 at the National cancer Institute (NCI), Egypt. Various patients’ and disease characteristics, treatment details and outcome data were reviewed. Results: Fifty patients’ records were included in the analysis with a median age of 6 years at diagnosis (range 3 - 18). According to the Chang staging system; 38%, 44%, 4%, and 14% were M0, M1, M2, and M3, respectively. All patients underwent primary surgery; gross total resection (with no residual) in 38%, near total resection (with residual ≤1.5 cm2) in 8%, subtotal resection (with residual > 1.5 cm2) in 34%, and 20% had only biopsy. All patients were treated by riskadapted craniospinal irradiation (CSI); high-risk patients were treated by CSI 36 Gy/20 fractions over 4 weeks followed by posterior fossa (PF) boost 18 Gy/10 fractions over 2 weeks (180 cGy per fraction), while standard-risk patients were treated by CSI 23.4 Gy/13 fractions over 2 and half weeks followed by PF boost 30.6 Gy/17 fractions over 3 and half weeks. Median overall treatment time (OTT) was 52 days. All patients received adjuvant CT; 47 patients (94%) received concomitant chemo radiotherapy (CCRT), while 4 patients (8%) only received neoadjuvant CT (NB: only one patient received all neoadjuvant, concomitant and adjuvant CT). With a median follow up time of 32.5 months, ranging from 6 to 104 months, the whole group estimates of the overall survival (OS) at 1, 3, and 5 years were 83%, 70%, and 64%, respectively, while, the progression-free survival (PFS) rates at 1, 3, and 5 years were 79%, 62%, and 57% respectively. Four patients relapsed. Neural-axis was the commonest site of relapse (3 patients). Both risk groups were equally represented in relapsed patients (2 standard risk & 2 high risk patients) and relapse took place within 2 years. In univariate analysis, performance status,extent of surgery, and post-operative residual tumor size were significant prognostic factors for OS. On the other hand, factors which affected the PFS included gender, extent of surgery, and post-operative residual tumor. Conclusion: Neural-axis relapse was the commonest site of relapse for pediatric MB patients. Extent of surgical resection, post-operative residual tumor, and gender are powerful prognostic factors. Maximal safe resection is the standard surgical approach for MB patients to achieve cure.