Second brain tumors following central nervous system radiotherapy in childhood

The second tumour (ST) occurrence is a relatively uncommon late complication of radiotherapy but represents one of the most significant issues, especially in childhood oncology. We describe our experience with patients who developed second brain neoplasm following cranial irradiation in childhood.

We identified nine patients who received radiotherapy owing to central nervous system tumour in childhood and subsequently developed the second brain tumour. The full clinical and radiological documentation and histopathological reports were reviewed. Risk factors such as age at irradiation, latency period to ST diagnosis, radiotherapy doses and volumes and other therapy methods were evaluated. We correlated the ST location with the three levels of irradiation dose (high, >40 Gy; medium, 25-40 Gy; and low <25 Gy).

Five meningiomas and four gliomas occurred as the ST after the mean time of 11.7 years after radiotherapy. The average age of children during irradiation was 4.6 years. The shorter latency time to the ST induction was found in children treated with chemotherapy (9 years vs 17.2 years). Seven STs developed in the area of high and moderate dose (>25 Gy), only two low-grade gliomas appeared in the low-dose region.

Our data suggest that the STs usually develop in the brain tissues that received doses >25 Gy in patients irradiated at a young age.

The low-dose volume seems not to be so significant for second brain neoplasm induction. Therefore, the modern intensity-modulated radiotherapy technique could be safely applied in paediatric patients.