title: 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.
abstract: OBJECTIVE
  To investigate whether the initial maximum standardized uptake value (SUVmax) on fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) has a prognostic significance in metastatic lung adenocarcinoma.
  
  
  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 SUVmax value, which was found as 11. Progression-free survival (PFS) rates for 3, 6, and 12 months 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 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 SUVmax 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 SUVmax (≤11) group/high SUVmax (>11) group, respectively.
  
  
  CONCLUSIONS
  Initial SUVmax 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.
authors.affiliation: Department of Internal Medicine, Division of Medical Oncology, Gaziantep Oncology Hospital, University of Gaziantep, Gaziantep, Turkey.
authors.forename: Tulay
authors.initials: T
authors.lastname: Kus
authors.affiliation: Department of Internal Medicine, Division of Medical Oncology, Gaziantep Oncology Hospital, University of Gaziantep, Gaziantep, Turkey.
authors.forename: Gokmen
authors.initials: G
authors.lastname: Aktas
authors.affiliation: Department of Internal Medicine, Division of Medical Oncology, Gaziantep Oncology Hospital, University of Gaziantep, Gaziantep, Turkey.
authors.forename: Alper
authors.initials: A
authors.lastname: Sevinc
authors.affiliation: Department of Internal Medicine, Division of Medical Oncology, Gaziantep Oncology Hospital, University of Gaziantep, Gaziantep, Turkey.
authors.forename: Mehmet Emin
authors.initials: ME
authors.lastname: Kalender
authors.affiliation: Department of Nuclear Medicine, University of Gaziantep, Gaziantep, Turkey.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Yilmaz
authors.affiliation: Department of Biostatistics, Faculty of Medicine, University of Gaziantep, Gaziantep, Turkey.
authors.forename: Seval
authors.initials: S
authors.lastname: Kul
authors.affiliation: Department of Medical Biology, Faculty of Medicine, University of Gaziantep, Gaziantep, Turkey.
authors.forename: Serdar
authors.initials: S
authors.lastname: Oztuzcu
authors.affiliation: Department of Radiology, Faculty of Medicine, University of Akdeniz, Antalya, Turkey.
authors.forename: Cemil
authors.initials: C
authors.lastname: Oktay
authors.affiliation: Department of Internal Medicine, Division of Medical Oncology, Gaziantep Oncology Hospital, University of Gaziantep, Gaziantep, Turkey.
authors.forename: Celaletdin
authors.initials: C
authors.lastname: Camci
keywords: 18F-fluorodeoxyglucose positron emission tomography/computed tomography; erlotinib; lung adenocarcinoma; maximum standardized uptake value; prognosis; treatment response