Reduced versus standard dose craniospinal irradiation with chemotherapy to treat medulloblastoma

Background: Current treatment for medulloblastoma involves craniospinal irradiation (CSI) with a radiation boost to the posterior fossa and adjuvant chemotherapy following surgical resection. Due to neurotoxic effects of CSI—particularly its impact on cognitive function and intelligence quotient (IQ)—recent efforts have focused on reducing CSI dosage. This systematic review compares standard-dose CSI (SDCSI) versus low-dose CSI (LDCSI) in terms of relapse rate, event-free survival (EFS), progression-free survival (PFS), and overall survival (OS). Methods: A systematic search was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Two reviewers independently screened studies for eligibility and extracted data on study design, patient demographics, CSI dosage, chemotherapy regimens, EFS, OS, relapse rates, and reported side effects. Results: Out of 749 identified studies, 24 met the inclusion criteria for this review. Reported 5-year EFS ranged from 27.3% to 83%, and 5-year OS ranged from 41 ± 8% to 94.7 ± 3.4%. Commonly reported adverse effects included hematologic toxicity, secondary malignancies, disease progression, nausea/vomiting, and cognitive impairment. IQ outcomes ranged from 71 to 98.6, with studies consistently showing that LDCSI was associated with a smaller decline in IQ compared to SDCSI. Factors such as age, molecular subgroup, and histological features were identified as important variables for risk stratification. Discussion: LDCSI combined with chemotherapy may provide sufficient treatment efficacy for medulloblastoma while mitigating neurocognitive decline. Future research should focus on optimizing chemotherapy regimens and refining treatment stratification based on molecular and histological subtypes, particularly in standard- versus high-risk patients.