Impact of Whole Body Radiation Dose After Therapy with 131I-Metaiodobenzylguanidine (MIBG)

Background:
Neuroblastoma is the most common pediatric extracranial solid tumor, with approximately 650 new cases each year presenting in the United States. The majority of neuroblastoma malignancies are found in the adrenal glands, endocrine structures above the kidneys. More than half of children with neuroblastoma present with widespread metastatic disease at diagnosis, with a poor chance for long-term survival. 131I-metaiodobenzylguanidine (MIBG) is a targeted radiopharmaceutical that is specifically taken up by neuroblastoma tumor cells, because it is similar in structure to adrenaline. MIBG has become an important agent to treat children with resistant and relapsed neuroblastoma. It is administered by vein and therefore is delivered to all the metastatic tumor sites. It is now being tested for upfront therapy of children with advanced neuroblastoma.

Although the MIBG is tumor-specific, it is metabolized and excreted over several days, and does result in exposure of the entire body to some radiation, which can result in low blood counts, infection, and bleeding tendency and also thyroid damage due to the uptake of radioactive iodine.

Project Goal:

In this study, we will analyze the whole body radiation dose and determine the impact on tumor response, as well as the toxic side effects and relation to other clinical patient factors, such as age, size, MIBG dose, hypothyroidism, low blood counts, and tumor extent and sites. Better understanding of the relation of the MIBG to the whole body radiation dose will allow more precise selection of MIBG dose for personalized treatment, thus minimizing side effects and maximizing effectiveness.