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Medulloblastoma with brain stem involvement: the impact of gross total resection on outcome
A Gajjar1, R A Sanford, R Bhargava
1Le Bonheur Children's Medical Center, Brain Tumor Team, Department of Hematology-Oncology, St. Jude Children's Research Hospital, Memphis, TN 38101-0318, USA. amar.gajjar@stjude.org
Insights
Gross total resection did not improve progression-free survival (PFS) in children with brain stem-invading medulloblastoma. Aggressive surgical resection is key, but the posterior fossa syndrome remains a concern, necessitating careful surgical risk assessment.
Area of Science:
- Pediatric Oncology
- Neurosurgery
- Clinical Research
Background:
- Medulloblastoma is a common pediatric brain tumor.
- Locally advanced medulloblastoma invading the brain stem presents unique surgical challenges.
- Extent of surgical resection is a critical factor in treatment outcomes.
Purpose of the Study:
- To evaluate the impact of gross total resection on progression-free survival (PFS) in pediatric patients with brain stem-invading medulloblastoma.
- To assess the relationship between extent of resection and postoperative morbidity, specifically posterior fossa syndrome.
- To analyze the risk-benefit ratio of aggressive surgical approaches in this patient subgroup.
Main Methods:
- Retrospective review of 40 pediatric patients with newly diagnosed, locally advanced medulloblastoma involving the brain stem.
- Classification of surgical resection extent: gross total, near-total, and subtotal.
- Analysis of progression-free survival (PFS) and incidence of posterior fossa syndrome in relation to resection extent.
- Subsequent therapies included craniospinal irradiation and chemotherapy.
Main Results:
- No significant difference in PFS was observed between gross total resection and any detectable residual tumor.
- 85% of patients achieved >90% resection, with 61% postirradiation PFS at 4-year follow-up.
- Posterior fossa syndrome occurred in 25% of cases, unrelated to the extent of resection.
Conclusions:
- True gross total resection was not associated with improved PFS compared to near-total or subtotal resection in this cohort.
- The high incidence of posterior fossa syndrome warrants careful consideration of surgical risks.
- Optimizing surgical strategy requires balancing maximal tumor removal with minimizing neurological deficits.
Abstract:
We studied the impact of gross total resection on progression-free survival (PFS) and postoperative morbidity in 40 children with locally advanced medulloblastoma characterized by tumor invading the brain stem. These patients represented 40% of children treated for newly diagnosed medulloblastoma at a pediatric oncology center over a 10-year period. All patients underwent aggressive initial surgical resection. Review of surgical and neuroimaging findings documented gross total resection in 13 cases, near-total resection (< 1.5 cm2 residual tumor on imaging) in 14 cases, and subtotal resection (> than 50% resection with > or = 1.5 cm2 residual) in 13 cases. Overall, 85% of patients had a > 90% resection. Subsequent therapy comprised craniospinal irradiation in all cases and chemotherapy on institutional or cooperative group protocols in 35 cases. At a median follow-up of 4 years, postirradiation PFS is 61% (SE = 10%). There was no difference in PFS for patients who underwent gross total resection compared to those with any detectable residual tumor (p > 0.70). The posterior fossa syndrome occurred in 25% of cases, and had no apparent relationship to the extent of resection (p > 0.5, exact test). In this series, true gross total resection was not associated with a PFS advantage when compared to strictly defined near-total and subtotal resection. Although there was no operative mortality, the frequency of the posterior fossa syndrome is of concern and emphasizes the need for careful consideration of the risk/benefit ratio in the surgical approach to this subgroup of patients.