Comparison of interim PET response to relapse vs. first-line treatment in children with classical Hodgkin lymphoma (HL) – contribution to the development of response criteria for relapsed HL

Introduction Criteria for standardized interpretation of PET response to treatment in HL have been established in large patient cohorts at first-line treatment using the Deauville scale or quantitative parameters like qPET (1). There is no systematic data yet, if the same criteria can be adopted also at relapse.

Methods Between 2007 and 2013, 2131 children and adolescents with classical HL have been included in the EuroNet-PHL-C1-trial. From this cohort, interim PET datasets after two cycles of first-line treatment (iPET-FL) were available on the central server from 177 patients who subsequently developed relapse. From 101 of these patients interim PET datasets after two cycles of relapse treatment (iPET-rel) were available. SUVpeak in the most FDG-avid tumor residual, SUVmean in the liver and qPET values were determined.

Results SUVpeak- and qPET-values of iPET-FL and iPET-rel were not systematically different (p=0.28 and 0.47). In 33/177 iPET-FL and 27/101 iPET-rel no quantification could be performed due to already completely normalised FDG-uptake. The median SUVpeak in the remaining iPET was 1.9 at FL and 2.2 at relapse, the median qPET 1.8 at iPET-FL and 1.7 at iPET-rel. The mean liver uptake increased slightly but systematically from 1.7±0.5 at iPET-FL to 2.0±0.6 at iPET-rel, p<0.001.

Conclusion qPET-values of iPET of patients during first-line and relapse treatment are nearly identical. This supports the current approach to use the established first-line response criteria also in the relapse treatment.

• References

• 1 Hasenclever. et. al. Eur J Nucl Med Mol Imaging. 2014; 41: 1301-8 .