Medulloblastoma with brain stem involvement: The impact of gross total resection on outcome

We studied the impact of gross total resection on progression-free survival (PFS) and postoperative morbidity in 40 children with locally advanced meduUoblastoma characterized by tumor invading the brain stem. These patients represented 40% of children treated for newly diagnosed meduUoblastoma at a pediatric oncology center over a 10-year period. All patients underwent aggressive initial surgical resection. Review of surgical and neuro-imaging findings documented gross total resection in 13 cases, near-total resection (< 1.5 cm² residual tumor on imaging) in 14 cases, and subtotal resection (> 50% resection with > 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.