Reply to Comment on: The UK Experience of a Treatment Strategy for Pediatric Metastatic Medulloblastoma Comprising Intensive Induction Chemotherapy, Hyperfractionated Accelerated Radiotherapy, and Response-Directed High-Dose Myeloablative Chemotherapy or Maintenance Chemotherapy (Milan Strategy)

Children treated for medulloblastoma and supratentorial primitive neuroectodermal tumor in Norway from 1974 through 2013: Unexplainable regional differences in survival

BACKGROUND

A previous study based on Norwegian Cancer Registry data suggested regional differences in overall survival (OS) after treatment for medulloblastoma (MB) and supratentorial primitive neuroectodermal tumor (CNS-PNET) in Norway. The purpose of the present study was to confirm in an extended cohort whether there were regional differences in outcome or not, and if so try to identify possible explanations.

MATERIAL AND METHODS

Data from patients aged 0-20 years diagnosed with and treated for MB/CNS-PNET at all four university hospitals in Norway from 1974 to 2013 were collected and compared.

RESULTS

Of 266 identified patients, 251 fulfilled inclusion criteria. MB was diagnosed in 200 and CNS-PNET in 51 patients. Five-year OS and event-free survival (EFS) were 59% and 52%, respectively. There was a significant difference in five-year OS and EFS between MB and CNS-PNET patients; 62% versus 47% (P =  0.007) and 57% versus 35% (P < 0.001). In multivariable analysis, two factors were found to significantly contribute to improved five-year OS and EFS, whereas one factor contributed to improved five-year OS only. Gross total resection (GTR) versus non-GTR (hazard ratio [HR] 0.53, P =  0.003; HR 0.46, P < 0.001) and cerebrospinal irradiation (CSI) versus non-CSI (HR 0.24, P < 0.001; HR 0.28, P < 0.001) for both, and treatment outside Oslo University Hospital for OS only (HR 0.64, P =  0.048).

CONCLUSION

Survival was comparable with data from other population-based studies, and the importance of GTR and CSI was confirmed. The cause for regional survival differences could not be identified.

Magnetic resonance imaging patterns of treatment-related toxicity in the pediatric brain: an update and review of the literature

Treatment-related neurotoxicity is a potentially life-threatening clinical condition that can represent a diagnostic challenge. Differentiating diagnoses between therapy-associated brain injury and recurrent disease can be difficult, and the immediate recognition of neurotoxicity is crucial to providing correct therapeutic management, ensuring damage reversibility. For these purposes, the knowledge of clinical timing and specific treatment protocols is extremely important for interpreting MRI patterns. Neuroradiologic findings are heterogeneous and sometimes overlapping, representing the compounding effect of the different treatments. Moreover, MRI patterns can be acute, subacute or delayed and involve different brain regions, depending on (1) the mechanism of action of the specific medication and (2) which brain regions are selectively vulnerable to specific toxic effects. This review illustrates the most common radiologic appearance of radiotherapy, chemotherapy and medication-associated brain injury in children, with special focus on the application of advanced MRI techniques (diffusion, perfusion and proton spectroscopy) in the diagnosis of the underlying processes leading to brain toxicity.