Patterns of local recurrence after intraoperative radiotherapy for advanced neuroblastoma

The purpose of this study was to retrospectively evaluate local recurrence patterns after intraoperative radiation therapy (IORT) combined with total or subtotal resection and intensive chemotherapy for advanced neuroblastoma.

The outcomes of 27 patients (14 boys and 13 girls) with advanced-stage neuroblastoma who received IORT as part of multimodality therapy between November 1988 and December 2006 were reviewed in order to evaluate the impact of IORT. Of particular interest was the local recurrence patterns observed.

Six patients relapsed in the abdominal area: three out of six relapsed adjacent to the radiation fields. Other three relapsed in the field of electron ports. Among them, one relapsed in paraspinal lymph nodes, which are behind the irradiated volume but out of the reach of the electron beam, while another relapsed in the lymph nodes of the mesocolon, which had been displaced outside the irradiation field at the time of IORT. The last case relapsed beside the vertebral column near the left ureter, which had been shielded by a lead plate. These three 'in-field' recurrences would have been irradiated if external opposite two-beam radiations had been performed, instead of electron beams.

In spite of a complete tumor control in the treated volume, some 'marginal' recurrences were observed. Further investigation--for example, a combination of IORT and external-beam radiotherapy--should be considered to achieve higher local control and decrease complication rates.