¹⁸F-FLT PET changes during radio - therapy combined with cetuximab in head and neck squamous cell carcinoma patients

Summary

Aim: Early treatment response of head and neck cancer to radiotherapy concomitant with cetuximab was monitored by repetitive PET imaging with the proliferation tracer ¹⁸F-FLT. Patients, methods: Five head and neck cancer patients, treated with radiotherapy and concomitant cetuximab following cetuximab induction, received four ¹⁸F-FLT PET-CT scans before and during treatment. Changes in SUV_peak, SUV_mean and CT- and PET-segmented gross tumour volumes were evaluated, as were correlations with immu- nohistochemical staining for Epidermal Growth Factor Receptor (EGFR) and Ki-67 (proliferation marker) in pre-treatment tumour biopsies. Results: ¹⁸F-FLT PET measured tumor responses to the induction dose of ce- tuximab varied from 43% SUV_peak decrease to 47% increase. After start of radiotherapy ¹⁸F-FLT PET parameters decreased significantly in all patients. No associations were found between PET parameters and EGFR or Ki-67 expression levels. Conclusion: Proliferation of head and neck carcinomas shows a varying response to cetuximab induction, but consistently decreases after addition of radiotherapy.

Zusammenfassung

Ziel: Frühe Behandlungsergebnisse der Kombination aus Strahlentherapie und Cetuximab bei Kopf-Hals-Karzinomen wurden mit Hilfe wiederholter PET-Bildgebung mit dem Proli- ferationsmarker ¹⁸F-FLT untersucht. Patienten, Methoden: Fünf Patienten mit Plattenepithelkarzinom im Kopf-Hals-Bereich, die zur Induktion mit Cetuximab und anschließend mit Strahlentherapie und Cetuximab behandelt worden waren, erhielten vier ¹⁸F-FLT-PET/CTs, vor und während der Behandlung. Änderungen im SUV_peak, SUV_mean und im auf CT und PET segmentierten Tumorvolumen wurden evaluiert. Ebenso wurden Korrelationen mit immunohistochemischen Färbungen des EGFR (epidermal growth factor receptor) und von Ki-67 (Proliferati- onsmarker) in vor der Behandlung entnommenen Tumorbiopsien untersucht. Ergebnisse: Die mit Hilfe von ¹⁸F-FLT PET gemessene Tumorresponse auf die Induktionsbehandlung mit Cetuximab variierte von einer SUV_peak-Abnahme von 43% bis zu einer Zunahme von 47%. Nach Beginn der Strahlentherapie nahmen die ¹⁸F-FLT-PET-Parameter bei allen Patienten signifikant ab. Es wurde kein Zusammenhang zwischen PET-Parame- tern und EGFR- oder Ki-67-Expression gefunden. Schlussfolgerung: Die Proliferationsrate von Kopf-Hals-Karzinomen zeigt eine unterschiedliche Reaktion auf die Induktionsbehandlung mit Cetuximab, nimmt aber konsistent nach Beginn der konkomitanten Strahlentherapie ab.

Keywords

[¹⁸F] fluorothymidine PET - head and neck cancer - cetuximab - radiotherapy - early response monitoring

Schlüsselwörter

[¹⁸F]-Fluorthymidin-PET - Kopf-Hals-Karzinom - Cetuximab - Strahlentherapie - Analyse frühzeitiger Behandlungsergebnisse

• References

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