The impact of PET and PET/CT on treatment planning and prognosis of patients with NSCLC treated with radiation therapy.

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.