Concordance in the interpretation of PET after chemotherapy in advanced stage Hodgkin lymphoma

Summary

The aim was to analyze the degree of agreement between the central review panel and the local PET interpretation within the HD15 trial and its impact on subsequent treatment and progression free survival. Patients, methods: The analysis set consisted of 739 patients with residues ≥ 2.5 cm after 6 or 8 cycles of BEACOPPesc from the HD15 trial performed by the German Hodgkin Study Group. The recommendation for or against further radiotherapy was based on the central [¹⁸F]FDG-PET interpretation. Central PET interpretation was compared to the local PET interpretation and concordance was measured using Cohen's Kappa coefficient. Prognostic impact of the analysis of concordance between local and central PET interpretations was evaluated using progression free survival (PFS); groups were compared with the log rank test. Results: The central panel rated 548 of 739 patients (74%) as PET negative. Of these, 513 were also rated as PET negative in the local PET interpretation. PET positivity was seen by central reviewers in the remaining 191 patients (26%), in concordance with local reviewers in 155 cases. Even though substantial agreement was found (Cohen's Kappa 0.81), the interpretation of the central PET review panel led to a different therapeutic recommendation in 71/739 (10%) patients. PFS was equally high in groups in which the therapeutic regime had been changed on the basis of the central panel decision. Conclusion: High concordance is found between local and central reviewers with regard to PET interpretation in residual tissue after intense chemotherapy. The existence of the central PET review panel allows the identification of additional patients as PET negative so that radiotherapy can be safely omitted (35 of 548 patients = 4.7%).

Zusammenfassung

Die PET mit FDG wird nach Chemotherapie beim fortgeschrittenen Hodgkin-Lymphom eingesetzt, um über eine konsolidierende Bestrahlung zu entscheiden. Ziel dieser Auswertung war es, die lokale und zentrale PET-Beurteilung in der HD15-Studie hinsichtlich übereinstimmung, Therapiekonsequenz und des Einflusses auf das progressionsfreie überleben zu untersuchen. Patienten, Methoden: Es wurden 739 Patienten mit Restgewebe von ≥ 2.5 cm nach 6 oder 8 Zyklen BEACOPPesc aus der HD15-Studie der German Hodgkin Study Group ausgewertet. Die Entscheidung für oder gegen die Bestrahlung basierte auf der Empfehlung des zentralen Panels. Die zentrale PET-Beurteilung wurde der lokalen PET-Interpretation gegenübergestellt und die übereinstimmung mit Hilfe des Cohen's Kappa gemessen. Die prognostische Bedeutung der übereinstimmung von lokaler und zentraler Beurteilung wurde durch das progressionsfreie überleben und den log-rank Test untersucht. Ergebnisse: Das zentrale PET-Panel erhob bei 74% der Patienten negative PETBefunde (548 von 739 Patienten). Von diesen waren 513 übereinstimmend mit der lokalen PET-Interpretation bewertet. PET-positives Restgewebe wurde vom zentralen Panel bei 191 Patienten (26%), gesehen, davon bei 155 Patienten in überstimmung mit der lokalen Interpretation. Auch wenn eine “substanzielle übereinstimmung” beobachtet wurde (Cohen's Kappa 0,81), führte die Interpretation durch das zentrale Panel bei 71/739 Patienten (10%) zu divergierenden therapeutischen Konsequenzen. Das progressionsfreie überleben war bei diesen Patienten mit divergierender PET-Interpretation vergleichbar hoch. Schlussfolgerung: Lokale und zentrale Interpretation der PET von Restgewebe nach Chemotherapie zeigte eine hohe übereinstimmung. Allerdings konnten durch das zentrale Review-Panel weitere Patienten identifiziert werden, bei denen sicher auf Bestrahlung verzichtet werden konnte (35 von 548 PET negativen Patienten = 4,7%).

Keywords

PET - interpretation - concordance - Hodgkin lymphoma

Schlüsselwörter

PET - Interpretation - übereinstimmung - Hodgkin-Lymphom

^* both authors contributed equally to this work

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