Abstract
Introduction
Studies in adults have shown that metabolic tumor volume (MTV) in fluorine-18 fluorodeoxyglucose
(18F-FDG) positron emission tomography (PET)/computed tomography (CT) is a strong predictor
of event-free survival (EFS) and overall survival (OS) in Hodgkin's lymphoma, often
outperforming clinical scores and molecular predictors. However, there very few studies
on pediatric Hodgkin's lymphoma (PHL), with conflicting results.
Objectives
This retrospective study was conducted to evaluate the feasibility of MTV assessment
in PHL and to assess its prognostic role, given the paucity of data from the developing
world and the technical expertise required.
Materials and Methods
Children with PHL, treated per EuroNet-PHL-C1 interim guidelines/C2 protocol at our
center from 2017 to 2020 who had baseline and interim PET (iPET) scan done at our
institution were included. MTV was measured in tumor areas with standardized uptake
value (SUVmax) ≥2.5. MTV and SUVmax were compared at diagnosis and after two chemotherapy
courses.
Results
Sixty-one children (male:female = 1.5:1; mean age: 10.10 years) were recruited and
categorized into four stages (SI: 11; SII: 15; SIII: 21; and SIV: 14) and three treatment
groups (TG1: 16; TG2: 11; and TG3: 34). Based on iPET, 47 and 14 children were adequate
and inadequate responders, respectively. At a median follow-up period of 54 months,
the OS was 96.7% and the EFS was 85.2%. The median SUVmax and MTV were both found
to increase with advancing disease stage with a positive correlation (r = 0.41; p = 0.002). The difference in the median MTV was statistically significant for SII
versus SIII (p = 0.004) but not for the median SUVmax (p = 0.13). Similarly, the difference in the median MTV was statistically significant
for TG2 versus TG3 (p = 0.001) but not for the median SUVmax (p = 0.06). The median MTV in baseline PET/CT with Deauville score–based treatment response
groups for adequate and inadequate responders was 98.35 (37.93–298.2) mL and 145 (84.43–463.5)
mL, respectively (p = 0.31), and for those with events versus no events, the median MTV was 304 (30.45–452.7)
mL and 105.35 (37.9–309.2) mL, respectively (p = 0.82).
Conclusion
Baseline PET/CT MTV showed better correlation than SUVmax in delineating stage and
treatment groups. However, MTV in isolation was not sensitive or specific enough in
prognosticating treatment response or EFS (relapse or death) in this study setting.
The addition of significant clinico-biochemical parameters with MTV for future studies
could enhance prognostication.
Keywords
18F-FDG PET/CT - event-free survival - metabolic tumor volume - overall survival - pediatric
Hodgkin's lymphoma - prognostication - standardized uptake value
