ABSTRACT
Neuroblastoma is highly sensitive to both chemotherapy and radiation therapy . The role of radiation therapy is generally limited to high-risk patients with metastatic disease, who sequentially undergo chemotherapy,
surgical resection of the primary disease, myeloablative chemotherapy with stem-cell rescue, radiation therapy, and 13-cis-retinoic acid . This extended treatment regimen produced 3-year event-free survival (EFS) rates of about 50% in two COG randomized trials and 66% in another study, which was significantly higher than the EFS obtained without the addition of myeloablative chemotherapy and 13-cis-retinoic acid (Gatcombe et al . 2009) . Radiation therapy was given following recovery from high-dose chemotherapy to the primary tumor bed and sites of metastasis still demonstrating activity on nuclear medicine Iodine-131 metaiodobenzylguanidine (MIBG) scan between the end of induction chemotherapy and the onset of myeloablative chemotherapy . Radiation dose in the current COG trial is 21 .6 Gy, with a boost to 36 Gy to any gross residual disease present in the primary tumor site after resection . Patients with metastatic disease, commonly to multiple bone sites, receive 21 .6 Gy to each site of metastasis . Radiation therapy is also usually effective for the occasional tumor that does not respond to chemotherapy and for palliation of recurrent disease . Targeted radionuclide therapy using high activity I-131 (18 mCi/ Kg) attached to MIBG has been shown to be well tolerated and effective in patients with persistent or recurrent disease after chemotherapy . The role of I-131-MIBG in the initial therapy of high-risk disease is being investigated (Quach et al . 2011) .
