Prognostic value of FDG-PET/CT in pediatric neuroblastoma

Objectives To explore the prognostic value of F-18 FDG-PET/CT in pediatric neuroblastoma patients.

Methods Comparative (mixed retro & prospective) study with 63 pathologically proved NB patients who were referred to nuclear medicine department, Children's Cancer Hospital, Egypt (CCHE), from Oct., 2009 till Jan. 2014, their age ranged from 2 to 156 months, with male to female ratio 1.4:1 & dominating high risk category (~65.1 %). They underwent F-18 FDG-PET/CT using standard technique for purpose of initial, post-therapy or follow up assessment. Clinico-pathological, radiological and follow up data were also collected. FDG uptake level was expressed in terms of maximum standardized uptake of the primary lesion against the maximum standardized uptake of the reference liver activity and maximum standardized uptake of the primary lesion stands alone where ROC curves marked cut off values of 1.95 & 2.05 respectively (both were almost double the reference hepatic activity).

Results The marked cut-off values were tested in respect to the established clinico-pathological features and the disease outcome. we found significant relationship between the Shimada classification and FDG uptake level ,using 2.05 (cut-off value of the max SUV of the primary lesion), where 88.9% of those with favourable histology exhibit low FDG tumor uptake , while on the contrary 51.9 % of those with unfavourable histology showed high FDG uptake level exceeding the cut-off value 2.05 (p-value=0.03).The rest of correlation of both cut-off values with the other clinico-pathological features showed prevalence of increased primary tumor uptake of FDG (almost equal to or above double the reference hepatic activity) among those with less favourable clinico-pathological features yet was not statistically significant. As a trial to quantitatively evaluate the impact of variable patterns of FDG accumulation on overall survival using the suggested cut-off values. Our results revealed higher risk for lower 2 years overall survival with increased tumor accumulation of FDG which was statistically significant when using max SUV of the primary/ max SUV of the hepatic activity ratio cut-off value (1.95) (p-value=0.05) and a trend was seen with max SUV of the primary lesion (p-value=0.07).

Conclusions PET-CT may be a valuable prognostic indicator where higher tracer accumulation of F-18 FDG seems to be linked to unfavorable histology & lower survival.