Explorative analyses on the value of interim PET for prediction of response in pediatric and adolescent non-Hodgkin lymphoma patients

Abstract

BackgroundThis study is to evaluate the predictive value of FDG-PET (PET) in pediatric and adolescent patients suffering from non-Hodgkin lymphoma (pNHL) in comparison to information provided by conventional imaging methods (CIM).MethodsImaging was performed at baseline and at interim (after 2 cycles of chemotherapy). The response assessment in PET was carried out visually and semi-quantitatively, the latter one by use of percentage decrease in SUVmax from baseline to interim (ΔSUVmax). The PET-based results were compared to the findings by CIM. Progression-free survival (PFS) was analyzed using Kaplan-Meier curves (KM) and log-rank test.ResultsThe final study included 16 patients (mean follow-up time, 60.2 months (range, 4.0 to 85.7 months)). Relapse occurred in four patients. Visual PET compared to CIM revealed higher sensitivity (3/4 vs 1/4) and NPV (6/7 vs 10/13), and equal PPV (3/9 vs 1/3), but lower specificity (6/12 vs 10/12) and accuracy (9/16 vs 11/16). False-positive findings in PET at interim were predominantly observed in patients presenting bulky disease (5/6), whereas CIM was true-negative in all of these cases. KM analyses revealed no significant differences in 5-year PFS neither for CIM (76.9% vs 66.7%; p = 0.67) nor for visual PET (85.7% vs 66.7%; p = 0.34) nor for ΔSUVmax (88.9% vs 57.1%; p = 0.12).ConclusionsThe predictive value of iPET in pediatric patients suffering from NHL was limited due to considerably high amount of false-positive findings, especially in patients suffering from bulky disease. However, due to our limited sample size, final conclusions cannot be drawn and, thus, call for further evaluation of PET in pNHL in larger and more homogenous patient series.

Can FDG‐PET replace biopsy for the evaluation of residual tumor in pediatric mature B‐cell non‐Hodgkin lymphoma?

“…4 In our study, the 18 FDG-PET sensitivity was 88.2% and the NPV was 86.6%. Similar results have been reported with an NPV of 80% to 100%, 10,11 making it a very good negative test and a reliable indicator of CR, 13,14 and suggesting the possibility to avoid biopsy from a residual mass if it is negative. 8,9,[15][16][17] FN results varied among different studies and ranged from 0% to 5%.…”

Value of18F-FDG PET and PET/CT for Evaluation of Pediatric Malignancies

“…However, interim 18 F-FDG PET/CT scans after 2-3 cycles of standard chemotherapy showed a relatively wide range of sensitivity (77.8%-100%) and specificity (54.5%-97.7%) ( Table 1) (26,38,45,46). This may be due to lack of consensus on the best timing of interim PET and the definition of objective response criteria for interpretation (47)(48)(49). Nevertheless, interim 18 F-FDG PET/CT has shown high negative predictive value, and therefore an early negative scan is a reliable indicator for therapy response (negative predictive value, 85.7%-100%; positive predictive value, 41.2%-85.7%) (26,38,45).…”

Prognostic Value and Clinical Impact of 18FDG-PET in the Management of Children with Burkitt Lymphoma after Induction Chemotherapy

“…The few studies previously performed on pediatric lymphomas patients ( 16 – 22 ) demonstrated a good NPV of 18 FDG-PET performed during treatment, with values ranging from 85 to 100% suggesting biopsy can be avoided if 18 FDG-PET was negative. The recent pediatric study by Furth et al ( 17 ) was conducted on 16 pediatric NHL patients and showed an overall NPV of 85.7%, rising to 100% when considering only BL ( n = 7). Similarly, studies dedicated to pediatric BL by Karantanis et al ( 23 ) and Riad et al ( 25 ) reported a 100% NPV of 18 FDG-PET after chemotherapy despite residual masses detected on CI.…”

“…Riad et al ( 25 ) described false-positive 18 FDG uptake in four of 28 pediatric patients with abdominal BL. In these studies, abnormal 18 FDG uptake was variously defined: uptake greater than background activity in surrounding tissue ( 19 , 23 , 24 ), or the mediastinal blood pool activity ( 17 ) or IHP criteria ( 18 ) for reference. In our study, 18 FDG-PET images were interpreted with the current consensual set of criteria recently recommended by the “Lugano recommendations” ( 10 , 11 ).…”