Background: Prior investigations suggest that neuroblastomas (NBL) that do not accumulate MIBG (MIBG non-avid) may have more favorable features compared to MIBG avid tumors. We compared clinical/biologic features and clinical outcomes between patients with MIBG non-avid vs. avid NBL.
Methods: A retrospective analysis was performed of patients with metastatic high- or intermediate-risk NBL treated on COG protocols A3973 or A3961, respectively. A3973 patients had baseline MIBG scans centrally reviewed (n=306). A3961 patients with bone metastasis at baseline were included (n=37). Comparisons of clinical/biological features according to MIBG avidity were made with chi-squared or Fisher exact tests. Event-free survival (EFS) was compared using log-rank tests and modeled using Cox models.
Results: Thirty of 343 patients (8.7%) in the analytic cohort had MIBG non-avid NBL (n=1 from A3961 and n=29 from A3973). Non-avid tumors were less likely to be adrenal primary tumors (34.5% vs. 57.2%; p = 0.02) or have bone metastases (36.7% vs. 61.7%; p = 0.008) and were more likely MYCN amplified (53.8% vs. 32.6%; p = 0.03). The rate of positivity for urine catecholamine levels (available from A3973 only) was lower in patients with non-avid NBL (66.7% vs. 91%; p < 0.001). Patients with MIBG non-avid NBL had a 5-year EFS of 50.0% compared to 38.7% for patients with MIBG avid NBL (p = 0.03). On backward-selected multivariate testing in high-risk patients, MIBG avidity was the sole adverse prognostic factor for EFS identified (hazard ratio 1.77; 95% confidence interval 1.04 – 2.99; p = 0.03); MYCN status, age, grade, MKI, and ploidy were not prognostic.
Conclusions: MIBG non-avid NBL represents a distinct clinical subgroup with lower rates of adrenal primary tumors, bone metastasis, and catecholamine secretion. Despite being more likely to have MYCN amplified tumors, patients with MIBG non-avid NBL have superior outcomes compared to patients with MIBG avid NBL.