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

PURPOSE: To investigate whether the initial maximum standardized uptake value (SUV(max)) on fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-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 (18)F-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 SUV(max) value, which was found as 11. Progression-free survival (PFS) rates for 3, 6, and 12 months were examined for SUV(max) 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 3 months 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 6 months 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 12 months 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 SUV(max) values ≤11. The PFS rates for 3, 6, and 12 months were 70.5%/28% (P=0.001, OR=9.0; 95% CI: 2.79–29.04), 61.7%/8% (P<0.001, OR=28.35; 95% CI: 5.5–143), and 52.9%/8% (P<0.001, OR=18.69; 95% CI: 3.76–92.9) for low SUV(max) (≤11) group/high SUV(max) (>11) group, respectively. CONCLUSION: Initial SUV(max) value on (18)F-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.