Aim: 18F fluoro-deoxy-glucose (FDG) positron emission tomography (PET)-imaging improves the diagnostic accuracy in staging non small cell lung cancer (NSCLC) with possible impact on survival. This prospective study aimed to investigate the impact of PET and PET/CT on treatment planning and prognosis in patients with NSCLC treated with radiation therapy.
Methods: From October 2003 to January 2008, 91 consecutive patients with proven NSCLC stage T1-4N0-3M0 (clinical stages: I-IIIb) underwent accelerated, twice daily radiation therapy in target splitting technique. 70 patients received chemotherapy before radiation therapy (76%). All patients underwent PET or PET/CT-imaging and were followed up for a median time of 30 months. Imaging findings were interpreted visually and a SUV cut-off of 2.5 was applied for delineation of tumor borders. Changes in staging and planning treatment volumes (PTV) due to PET or PET/CT-imaging and survival were defined as primary study endpoints. The impact of tumor-type, stage, age, gender, weight loss and FDG-uptake in PET imaging as measured by the standardized uptake value (SUV) on survival were analysed as secondary endpoints.
Results: PET imaging provided additional diagnostic information over CT alone in 20% (N.=18) of our study population, leading to upstaging in 17% of them, respectively. In 5 patients (5.5% of 91) atelectasis could be separated from tumor tissue, PTV was altered in 9% (N.=8). 39 patients (43%) died during the observation period, mean overall survival was 32.3 months (95% Confidence intervalI 27.6-37.1) and tumor specific survival was 36.9 months (95 % CI 32.0-42.0), respectively. One- and two year survival rates reached 90.1% and 67.7%, respectively. Multivariate analysis did not reveal any significant prognostic impact of tumor-type, stage, age, gender or FDG-uptake as given by SUVmax (mean 13.6±6.8) or SUVmean (mean 5.5±1.6).
Conclusion: The use of FDG-PET- and PET/CT-imaging provided incremental information relevant for treatment-planning in about 10 % of patients with NSCLC undergoing accelerated radiation therapy with curative intent. This prospective trial did not provide evidence for the assumption that the SUV might be an independent predictor of outcome.