Brain-sparing radiotherapy for neuroblastoma skull metastases

Neuroblastoma (NB) frequently metastasizes to the skull, often diffusely involving the calvarium and skull base. Radiotherapy may enhance local control; however, irradiating the brain is undesirable in young patients. The purpose of this study was to describe the technique, outcome and toxicities in patients with high risk NB metastatic to the skull treated with brain-sparing skull radiotherapy (BSRT).

Between 1999 and 2007, 31 patients with INSS stage four high risk NB, aged 2-32 years (median 6 years), underwent multimodality therapy, including radiotherapy to the whole skull using a brain-sparing technique never previously described in this population. Dosimetric analyses were performed to compare the BSRT technique to a whole brain radiotherapy (WBRT) technique. Patients were either treated to consolidate upfront induction therapy (n = 22) or to palliate relapsed disease (n = 9).

Thirty of 31 patients (97%) completed the full course of BSRT. Median follow-up was 19 months (range 1-83 months). Radiographic response to therapy was noted in 89% of patients. The actuarial rate of disease control in the skull was 89% and 60% 1 year after starting BSRT in patients treated in consolidation and for palliation, respectively. BSRT delivered half of the mean radiation dose to the brain when dosimetrically compared to whole brain radiotherapy. Few patients experienced significant toxicity.

BSRT in NB patients with diffuse skull metastases offers dosimetric advantages over WBRT and results in good local control when used in the consolidative setting. The technique is well tolerated and while toxicity appears acceptable, longer follow-up is necessary.