Utility of fluorodeoxyglucose-positron emission tomography in the identification of new lesions in lung cancer patients for the assessment of therapy response.

ABSTRACT

PURPOSE: Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) has added positron emission tomography (PET) as an optional complement for the detection of new lesions. In this study, we evaluate the utility of fluorodeoxyglucose (FDG)-PET in the identification of new lesions and progressive disease not recognized on computed tomography (CT) in patients with nonsmall cell lung cancer (NSCLC) undergoing therapy. MATERIALS AND METHODS: Seventy patients (30 female, 40 male; mean age 67±14 years, range, 39-94 years) with NSCLC underwent FDG-PET before and after chemotherapy and/or radiotherapy, whereas 69 patients underwent CT imaging. Overall (OS) and progression-free survivals (PFS) were calculated for RECIST 1.1 with CT alone, RECIST 1.1 with PET for the identification of new lesions, visual PET, and semiquantitative PET using a change in standardized uptake value ranging from -15 to -50%. RESULTS: PET identified new lesions in 26 patients, resulting in 10 patients (14.5%) being upgraded to progressive disease. The combination of CT and PET for the detection of new lesions improved the prediction of survival (OS P=0.0491 for all stages and P=0.0033 for stage IV; PFS P=0.0045 for stage IV) compared with CT imaging alone (OS P=0.1362 for all stages and P=0.1625 for stage IV; PFS P=0.0632 for stage IV). Furthermore, a change in standardized uptake value of -35% was the most discriminative for the prediction of survival for the semiquantitative PET approach (OS P=0.0393 for all stages, P=0.0051 for stage IV; PFS P=0.0092 for stage IV) and more discriminative than the visual PET approach (OS P=0.2699 for all stages, P=0.0105 for stage IV; PFS P=0.014 for stage IV). CONCLUSION: FDG-PET is helpful in identifying new lesions in NSCLC patients, resulting in the improved assessment of therapy response with CT imaging combined with FDG-PET compared with CT imaging alone. Although RECIST 1.1 includes FDG-PET only as an optional adjunct, we recommend the implementation of PET imaging in the assessment of therapy response.