UCSF

Background

Long-term CT follow-up studies are required in pediatric patients who have received intraoperative radiation therapy (IORT) and external beam radiation therapy (EBRT) to assess vascular toxicities and to determine the exact complication rate.

Objective

To analyze with CT the effects of radiation therapy (RT) on the growth of the aorta in neuroblastoma patients.

Materials and methods

Abdominal CT scans of 31 patients with intraabdominal neuroblastoma (stage II-IV), treated with RT (20 IORT+/-EBRT, 11 EBRT alone), were analyzed retrospectively. The diameter of the abdominal aorta was measured before and after RT. These data were compared to normal and predicted normal aortic diameters of children, according to the model of Fitzgerald, Donaldson and Poznanski (aortic diameter in centimeters = 0.844 + 0.0599 x age in years), and to the diameters of a control group of children who had not undergone RT. Statistical analyses for the primary aims were performed using the chi-squared test, t-test, Mann-Whitney test, nonparametric Wilcoxon matched-pairs test and analysis of variance for repeated measures. Clinical files and imaging studies were evaluated for signs of late vascular complications of neuroblastoma patients who had received RT.

Results

The mean diameter before and after RT and the growth of the aorta were significantly lower than expected in patients with neuroblastoma (P<0.05 for each) and when compared to the growth in a control group with normal and nonirradiated aortas. Among the patients who had received RT, there was no difference due to the type of RT. Seven patients from the IORT+/-EBRT group developed vascular complications, which included hypertension (five), middle aortic syndrome (two), death due to mesenteric ischemia (one) and critical aortic stenosis, which required aortic bypass surgery (two).

Conclusion

Patients with neuroblastoma who had received RT showed impaired growth of the abdominal aorta. Significant long-term vascular complications occurred in seven patients who received IORT+/-EBRT. Thus, CT evaluation of patients with neuroblastoma who receive RT should include not only reports of changes in tumor extension, but also documentation of perfusion, and the size and growth of the aorta and its branches over time.