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

B. Hoeben, E. Troost, J. Bussink, C. van Herpen, W. Oyen and J. Kaanders

Bianca A.W. Hoeben, MD Radboud University Medical Center, Department of Radiation Oncology 874, P. O. Box 9101, 6500 HB Nijmegen, The Netherlands, Tel. +31/24/361 45 15; Fax +31/24/361 07 92, E-mail: b.hoeben@radboudumc.nl.
Jan, 2014



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 SUVpeak, SUVmean and CT- and PET-segmented gross tumour volumes were evaluated, as were correlations with immunohistochemical 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 cetuximab varied from43\% SUVpeak 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.