Purpose or Case Report: Despite significant advances in delivering dose-intensive and myeloablative therapy with hematopoietic stem cell support, the survival for patients presenting with metastatic neuroblastoma remains poor, with a 3 year event free survival (EFS) of about 60%. Modern treatment protocols are based on risk stratification which incorporates age of diagnosis, tumor stage, tumor histology, and molecular and cytogenetics including MYCN amplification. ¹⁸F-FDG PET/CT can play a role in disease staging and follow up. The purpose of this study was to report FDG PET findings in a cohort of children with neuroblastoma and assess for predictive associations with MYCN amplification status.
Methods & Materials: A single institution retrospective review was performed to identify all patients with newly diagnosed neuroblastoma for whom both pre-therapy ¹⁸F-FDG PET/CT and MYCN FISH were obtained between July 2006 and July 2019. All FDG-PET examinations had been performed utilizing 0.1-0.14 mCi/kg of FDG with imaging performed approximately 1 hour after radiopharmaceutical administration. Using the PET-edge tool in MIM (MIM Software; Cleveland, OH), a single observer drew regions of interest around the primary tumor to measure SUVmax, SUVmean, tumor volume, and total lesional glycolysis (TLG, SUVmean x tumor volume). All measurements were reviewed and adjusted as needed by a board certified Radiologist. Student’s t-test was used for comparisons of means.
Results: A total of 45 patients were identified. Thirteen (29%) patients had MYCN amplification. The mean age at diagnosis was 2.7 years ± 1.9 [standard deviation]. SUVmax ranged from 1.1 to 11.2 (mean 4.7 ± 2.3). Patients with MYCN amplification were older than those without MYCN amplification (3.6 ± 2.3 vs 2.4 ± 1.6 years, p = 0.04). Mean SUVmax (5.9 ± 2.4 vs 4.2 ± 2.1, p = 0.028), tumor volume (438 ± 335 mL vs 95 ± 96mL, p<0.0001), and TLG (1056 ± 845 vs 226 ± 329, p<0.0001) were significantly higher in MYCN amplified tumors versus non amplified tumors. SUVmax of the primary tumor was higher in patients with bone marrow metastases than those without (5.6 ± 2.0 vs 4.0 ± 2.3, p = 0.017).
Conclusions: On average, MYCN amplified neuroblastomas are larger and more metabolically active than MYCN non-amplified tumors. FDG PET may provide prognostic value in newly diagnosed neuroblastoma.