Positron Emission Tomography/Computed Tomography Assessment After Immunochemotherapy and Irradiation Using the Lugano Classification Criteria in the IELSG-26 Study of Primary Mediastinal B-Cell Lymphoma

Publication date: 1 January 2017
Source:International Journal of Radiation Oncology*Biology*Physics, Volume 97, Issue 1
Author(s): Luca Ceriani, Maurizio Martelli, Maria K. Gospodarowicz, Umberto Ricardi, Andrés J.M. Ferreri, Annalisa Chiappella, Caterina Stelitano, Monica Balzarotti, Maria E. Cabrera, David Cunningham, Attilio Guarini, Pier Luigi Zinzani, Luca Giovanella, Peter W.M. Johnson, Emanuele Zucca
PurposeTo assess the predictive value of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) for disease recurrence after immunochemotherapy (R-CHT) and mediastinal irradiation (RT), using the recently published criteria of the Lugano classification to predict outcomes for patients with primary mediastinal large B-cell lymphoma.Methods and MaterialsAmong 125 patients prospectively enrolled in the IELSG-26 study, 88 were eligible for central review of PET/CT scans after completion of RT. Responses were evaluated using the 5-point Deauville scale at the end of induction R-CHT and after consolidation RT. According to the Lugano classification, a complete metabolic response (CMR) was defined by a Deauville score (DS) ≤3.ResultsThe CMR (DS1, -2, or -3) rate increased from 74% (65 patients) after R-CHT to 89% (78 patients) after consolidation RT. Among the 10 patients (11%) with persistently positive scans, the residual uptake after RT was slightly higher than the liver uptake in 6 patients (DS4; 7%) and markedly higher in 4 patients (DS5; 4%): these patients had a significantly poorer 5-year progression-free survival and overall survival. At a median follow-up of 60 months (range, 35-107 months), no patients with a CMR after RT have relapsed. Among the 10 patients who did not reach a CMR, 3 of the 4 patients (positive predictive value, 75%) with DS5 after RT had subsequent disease progression (within the RT volume in all cases) and died. All patients with DS4 had good outcomes without recurrence.ConclusionsAll the patients obtaining a CMR defined as DS ≤3 remained progression-free at 5 years, confirming the excellent negative predictive value of the Lugano classification criteria in primary mediastinal large B-cell lymphoma patients. The few patients with DS4 also had an excellent outcome, suggesting that they do not necessarily require additional therapy, because the residual ¹⁸F-fluorodeoxyglucose uptake may not reflect persistent lymphoma.



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