Intraoperative radiation therapy for advanced neuroblastoma: the problem of securing the IORT field

The purpose of this study is to evaluate the efficacy of intraoperative radiation therapy (IORT) and the problem of securing the IORT field in advanced pediatric neuroblastoma. Between 1996 and 2005, 12 children received IORT for advanced pediatric neuroblastoma patients. Electron beam energies ranged from 10 to 12 MeV and median dose was 10 Gy (8-12 Gy). All of them had surgery with IORT against the primary tumor site and the abdominal aorta surroundings. A gross total resection (GTR) was achieved in 10 patients and subtotal resection (STR) was two patients. All of 12 patients were classified as high risk. Nine patients were alive 17-120 (mean 48 months) after diagnosis. Local tumor control was achieved in 100% of patients, of whom one experienced local recurrence outside the IORT field. At the operation, it was difficult to secure the IORT field because of the angle of the radiation cylinder in three patients. One of the three of these patients experienced local recurrence outside of the IORT field in the upper side of superior mesenteric artery and two of three patients had an external beam radiation after surgery, and there was no local recurrence. One patient had a postoperative ileus, and one patient had transient diarrhea and hydronephrosis. For advanced neuroblastoma patients, IORT produced excellent local control after surgery. However, there is a problem of securing the IORT field. For local control, it is necessary to add an external beam radiation after IORT when it is difficult to secure the IORT field.