Diagnostic and staging impact of radiotherapy planning FDG-PET-CT in non-small-cell lung cancer

Background and purpose: To evaluate whether FDG-PET performed for radiotherapy (RI) planning can detect disease progression, compared with staging PET. Materials and methods: Twenty-six patients with newly-diagnosed non-small-cell lung cancer underwent planning PET-CT for curative RT within 8 weeks (mean: 33 14 days) of staging PET-CT. Progressive disease (PD) was defined as > 25% increase in tumour size (transaxial) or volume, as delineated by SUV threshold of 2.5, or new sites (SUV > 2.5). Results: The planning PET detected PD in 16 patients (61%), compared to four patients (15%) by CT component of PET-CT. The mean scan interval was longer in patients with progression: 40 +/- 12 days, compared to 22 +/- 11 days without progression. Planning PET detected PD in 13/17 (76%), 12/14 (86%) and 7/7 patients if the interval was >= 4, 5 and 6 weeks, respectively, compared with 3/9 patients if interval < 4 weeks. Planning PET detected PD in primary metabolic volume in seven patients, 20 new nodal sites in 12 new nodal stations and nine patients, five extra-nodal sites in five patients. This resulted in upstaging in nine patients (35%): stage IIIA in three, IIIB in three and IV in three. Conclusions: RT-planning FDG-PET can provide incremental diagnostic information and may impact on staging in a significant number of patients. (C) 2011 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 101 (2011) 284-290