Prognostic impact of initial maximum standardized uptake value of 18F-FDG PET/CT on treatment response in patients with metastatic lung adenocarcinoma treated with erlotinib

Tulay Kus,1 Gokmen Aktas,1 Alper Sevinc,1 Mehmet Emin Kalender,1 Mustafa Yilmaz,2 Seval Kul,3 Serdar Oztuzcu,4 Cemil Oktay,5 Celaletdin Camci1 1Department of Internal Medicine, Division of Medical Oncology, Gaziantep Oncology Hospital, 2Department of Nuclear Medicine, 3Department of Biostatistics, Faculty of Medicine, 4Department of Medical Biology, Faculty of Medicine, University of Gaziantep, Gaziantep, 5Department of Radiology, Faculty of Medicine, University of Akdeniz, Antalya, Turkey Purpose: To investigate whether the initial maximum standardized uptake value (SUVmax) on fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) has a prognostic significance in metastatic lung adenocarcinoma.Patients and methods: Sixty patients (24 females, mean age: 57.9±12 years) with metastatic stage lung adenocarcinoma who used erlotinib and underwent 18F-FDG PET/CT at the time of diagnosis between May 2010 and May 2014 were enrolled in this retrospective study. The patients were stratified according to the median SUVmax value, which was found as 11. Progression-free survival (PFS) rates for 3, 6, and 12months were examined for SUVmax values and epidermal growth factor receptor (EGFR) mutation status.Results: The number of EGFR-sensitizing mutation positive/negative/unknown was 26/17/17, respectively, and the number of patients using erlotinib at first-line, second-line, and third-line therapy was 15, 31, and 14 consecutively. The PFS rates of EGFR mutation positive, negative, and unknown patients for 3months were 73.1%, 35.3%, and 41.2% (P=0.026, odds ratio [OR]=4.39; 95% confidence interval [CI]: 1.45–13.26), respectively. The PFS rates of EGFR positive, negative, and unknown patients for 6months were 50%, 29.4%, and 29.4% (P=0.267, OR: 2.4; 95% CI: 0.82–6.96), respectively. The PFS rates of EGFR positive, negative, and unknown patients for 12months were 42.3%, 29.4%, 23.5% (P=0.408, OR: 2.0; 95% CI: 0.42–5.26), respectively. Thirty-one of 60 patients had SUVmax values ≤11. The PFS rates for 3, 6, and 12months were 70.5%/28% (P=0.001, OR=9.0; 95% CI: 2.79–29.04), 61.7%/8% (P11) group, respectively.Conclusion: Initial SUVmax value on 18F-FDG PET/CT is found to be a prognostic factor anticipating the response to erlotinib for 3, 6, and 12-month rates of PFS in both EGFR-sensitizing mutation and wild-type tumor group. Keywords: lung adenocarcinoma, erlotinib, 18F-fluorodeoxyglucose positron emission tomography/computed tomography, maximum standardized uptake value, treatment response, prognosis