I. Hazzard1, M. Georgies1, M. Bali1, E. Tabaie1, E. Frezza1 1California Northstate University, College Of Medicine, Elk Grove, CA, USA
Introduction: Treatment of medulloblastoma entails craniospinal irradiation (CSI) with a radiation boost to the posterior fossa and chemotherapy after surgical resection. However, due to its detrimental neurotoxic effects which can lead to decreased intelligence quotients (IQ), there have been recent efforts to reduce CSI. We aim to systematically review standard-dose (SD) CSI versus low-dose (LD) CSI for medulloblastoma through analysis of relapse rate, event-free survival (EFS), progression-free survival, and overall survival (OS).
Methods: Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were used to perform a search. Reviewers screened studies for eligible criteria and extracted data on study parameters, patient demographics, EFS, PFS, OS, CSI dosage, chemotherapy regimen, relapse rate, number of deaths, and side effects. A thorough literature review was performed. Meta-analysis of eligible studies was conducted using Cochrane RevMan web application.
Results: 24 out of 749 studies identified from the databases were selected for our systematic review. The lowest 5-year EFS was 27.3% and the highest 5-year EFS was 83%. The lowest 5-year OS was 41 ± 8% and the highest 5-year OS was 94.7 ± 3.4%. LD CSI had a higher 5-year OS compared to SD CSI (p = 0.0281). Results of the three studies eligible for meta-analysis favored LD CSI compared to SD CSI with an overall odds ratio of 1.15 (95% CI 0.63 – 2.09, p = 0.66). LD CSI had significantly lower relapse rate (14.5%) than SD CSI (20.6%) (p = 0.0475, 95% CI: 2.128 to 32.15) when comparing weighted means between studies. Hematological toxicity, secondary malignancy, progressive disease, nausea/vomiting, and cognitive impairment were the most reported side effects. The lowest IQ reported was 71 and the highest IQ reported was 98.6. Studies reported LD CSI to have a lower decline in IQ compared to SD CSI. Age, molecular subgroup, and histological morphology can inform risk stratification in medulloblastoma.
Conclusion: Low-dose craniospinal irradiation therapy with the addition of chemotherapy is sufficient in treating patients with medulloblastoma. LD CSI is associated with improved overall survival and significantly fewer relapses compared to standard-dose CSI. Further studies assessing the impact of varying chemotherapy regimens to treat medulloblastoma is necessary.