@article {Hoeben532, author = {Bianca A.W. Hoeben and Esther G.C. Troost and Paul N. Span and Carla M.L. van Herpen and Johan Bussink and Wim J.G. Oyen and Johannes H.A.M. Kaanders}, title = {18F-FLT PET During Radiotherapy or Chemoradiotherapy in Head and Neck Squamous Cell Carcinoma Is an Early Predictor of Outcome}, volume = {54}, number = {4}, pages = {532--540}, year = {2013}, doi = {10.2967/jnumed.112.105999}, publisher = {Society of Nuclear Medicine}, abstract = {This prospective study used sequential PET with the proliferation tracer 3'-deoxy-3'-18F-fluorothymidine (18F-FLT) to monitor the early response to treatment of head and neck cancer and evaluated the association between PET parameters and clinical outcome. Methods: Forty-eight patients with head and neck cancer underwent 18F-FLT PET/CT before and during the second and fourth weeks of radiotherapy or chemoradiotherapy. Mean maximum standardized uptake values for the hottest voxel in the tumor and its 8 surrounding voxels in 1 transversal slice (SUVmax(9)) of the PET scans were calculated, as well as PET-segmented gross tumor volumes using visual delineation (GTVVIS) and operator-independent methods based on signal-to-background ratio (GTVSBR) and 50\% isocontour of the maximum signal intensity (GTV50\%). PET parameters were evaluated for correlations with outcome. Results: 18F-FLT uptake decreased significantly between consecutive scans. An SUVmax(9) decline >= 45\% and a GTVVIS decrease >= median during the first 2 treatment weeks were associated with better 3-y disease-free survival (88\% vs. 63\%, P = 0.035, and 91\% vs. 65\%, P = 0.037, respectively). A GTVVIS decrease >= median in the fourth treatment week was also associated with better 3-y locoregional control (100\% vs. 68\%, P = 0.021). These correlations were most prominent in the subset of patients treated with chemoradiotherapy. Because of low 18F-FLT uptake levels during treatment, GTVSBR and GTV50\% were unsuccessful in segmenting primary tumor volume. Conclusion: In head and neck cancer, a change in 18F-FLT uptake early during radiotherapy or chemoradiotherapy is a strong indicator for long-term outcome. 18F-FLT PET may thus aid in personalized patient management by steering treatment modifications during an early phase of therapy.}, issn = {0161-5505}, URL = {https://jnm.snmjournals.org/content/54/4/532}, eprint = {https://jnm.snmjournals.org/content/54/4/532.full.pdf}, journal = {Journal of Nuclear Medicine} }