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Metachronous medulloblastoma and glioblastoma: Implications for clinical and technical aspects of re-irradiation
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Abstract
A seven-year-old male underwent surgical resection and chemoradiation for average risk medulloblastoma; twelve years later, the presence of a necrotic and infiltrative mass in the same area and invading the brainstem prompted a subtotal resection. Pathology was indicative of glioblastoma. He was then treated with concurrent temozolomide and using biologically effective dose calculations for gross residual tumor tissue in the brainstem as well as brainstem tolerance, a radiotherapy dose of 3750[[ce:hsp sp="0.25"/]]cGy was chosen, fractionated in twice-daily fractions of 125[[ce:hsp sp="0.25"/]]cGy each. The gross tumor volume was expanded with a 5[[ce:hsp sp="0.25"/]]mm margin to the planning target volume, which was also judiciously subtracted from the normal brainstem. He completed his radiotherapy course with subsequent imaging free of residual tumor and continued adjuvant temozolomide and remains under follow-up surveillance. This case underscores the rarity of metachronous medulloblastoma and glioblastoma, of which only five known cases heretofore have been described. We discuss the technicalities of radiotherapy planning in this patient, including common hurdles for radiation oncologists in similar patients.
Abstract
A seven-year-old male underwent surgical resection and chemoradiation for average risk medulloblastoma; twelve years later, the presence of a necrotic and infiltrative mass in the same area and invading the brainstem prompted a subtotal resection. Pathology was indicative of glioblastoma. He was then treated with concurrent temozolomide and using biologically effective dose calculations for gross residual tumor tissue in the brainstem as well as brainstem tolerance, a radiotherapy dose of 3750[[ce:hsp sp="0.25"/]]cGy was chosen, fractionated in twice-daily fractions of 125[[ce:hsp sp="0.25"/]]cGy each. The gross tumor volume was expanded with a 5[[ce:hsp sp="0.25"/]]mm margin to the planning target volume, which was also judiciously subtracted from the normal brainstem. He completed his radiotherapy course with subsequent imaging free of residual tumor and continued adjuvant temozolomide and remains under follow-up surveillance. This case underscores the rarity of metachronous medulloblastoma and glioblastoma, of which only five known cases heretofore have been described. We discuss the technicalities of radiotherapy planning in this patient, including common hurdles for radiation oncologists in similar patients.
Keywords
Medulloblastoma; Glioblastoma; Re-irradiation; Brainstem tolerance; Toxicity
About this articleTitle
Metachronous medulloblastoma and glioblastoma: Implications for clinical and technical aspects of re-irradiation
Journal
Reports of Practical Oncology and Radiotherapy
Issue
Pages
84-89
Published online
2016-01-01
DOI
10.1016/j.rpor.2015.10.002
Bibliographic record
Rep Pract Oncol Radiother 2016;21(1):84-89.
Keywords
Medulloblastoma
Glioblastoma
Re-irradiation
Brainstem tolerance
Toxicity
Authors
Vivek Verma
Rajesh R. Kulkarni
Abhijeet R. Bhirud
Nathan R. Bennion
Rodney D. McComb
Chi Lin