Differential (18)F-FDG and (18)F-FLT Uptake on Serial PET/CT Imaging Before and During Definitive Chemoradiation for Non-Small Cell Lung Cancer.
We aimed to prospectively observe cellular metabolism and proliferation in patients with non-small-cell lung cancer (NSCLC) during radical chemoradiation therapy using serial PET/CT with (18)F-FDG and 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT).


METHODS
Twenty patients with stage I-III NSCLC and candidates for radical chemoradiation therapy (60 Gy in 30 fractions over 6 wk) were recruited. (18)F-FDG and (18)F-FLT PET/CT were performed at baseline and during therapy (weeks 2 and 4). Tumor response was assessed semiquantitatively and using visual response criteria.


RESULTS
The median and range for primary tumor volume (cm(3)) at baseline on (18)F-FDG were 28 and 2-241, respectively, and on (18)F-FLT 31 and 2-184, respectively. At week 2, (18)F-FDG was 26 (range, 2-164), and (18)F-FLT was 11 (range, 0-111). At week 4, (18)F-FDG was 19 (1-147), and (18)F-FLT was 7 (0-48). The median and range of maximum standardized uptake value (SUVmax) at baseline on (18)F-FDG were 14 and 4-31, respectively, and on (18)F-FLT 6 and 2-12, respectively. Week 2 (18)F-FDG median SUVmax was 10 (2-31), and (18)F-FLT median SUVmax was 3 (1-15); week 4 (18)F-FDG median SUVmax was 10 (2-15), and (18)F-FLT median SUVmax was 2 (2-9). There was fair agreement between visual tumor response on (18)F-FDG and (18)F-FLT during therapy (Cohen's unweighted κ statistic, 0.27 at week 2 and 0.355 at week 4). Cerebral metastases were detected on 1 baseline (18)F-FLT scan, resulting in palliative management. Progressive disease was detected on week 2 scans in 3 patients, resulting in changes to radiation therapy (2 patients) and treatment intent (1 patient).


CONCLUSIONS
This study demonstrates that (18)F-FLT PET/CT is a more sensitive tracer of early treatment response than (18)F-FDG PET/CT. The ability of these tracers to detect distinct biologic processes may lead to their use as biomarkers for personalized radiation therapy and prognosis in the future.
Radiation Therapy, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia Department of Medical Imaging and Radiation Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia Sir Peter MacCallum Department of Oncology, University of Melbourne, Victoria, Australia sarah.everitt@petermac.org.
Sarah J
SJ
Everitt
Sir Peter MacCallum Department of Oncology, University of Melbourne, Victoria, Australia Division of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia.
David L
DL
Ball
Sir Peter MacCallum Department of Oncology, University of Melbourne, Victoria, Australia Centre for Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia.
Rodney J
RJ
Hicks
Department of Medical Imaging and Radiation Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia Centre for Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia.
Jason
J
Callahan
Division of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia.
Nikki
N
Plumridge
Centre for Biostatistics and Clinical Trials, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; and.
Marnie
M
Collins
Centre for Biostatistics and Clinical Trials, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; and.
Alan
A
Herschtal
Centre for Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia.
David
D
Binns
Department of Medical Imaging and Radiation Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia Sir Peter MacCallum Department of Oncology, University of Melbourne, Victoria, Australia Department of Physical Sciences, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia.
Tomas
T
Kron
Department of Medical Imaging and Radiation Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia.
Michal
M
Schneider
Sir Peter MacCallum Department of Oncology, University of Melbourne, Victoria, Australia Division of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia.
Michael
M
MacManus
D000368:Aged; D000369:Aged, 80 and over; D001692:Biological Transport; D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D059248:Chemoradiotherapy; D015224:Dideoxynucleosides / Q000378:metabolism*; D018450:Disease Progression; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D016019:Survival Analysis; D014057:Tomography, X-Ray Computed
D015224:Dideoxynucleosides; D019788:Fluorodeoxyglucose F18; C002854:alovudine
FDG: 18F-fluorodeoxyglucose; FLT: 18F-fluorodeoxythymidine; non-small cell lung cancer; positron emission tomography; radiation therapy