title: Role of FDG PET/CT in assessing response to targeted therapy in metastatic lung cancers: Morphological versus metabolic criteria.
abstract: BACKGROUND
  Targeted therapeutic agents are indicated in metastatic lung cancers. These being receptor specific therapies, manifestation of response can be best assessed by estimating the metabolic activity of tumor, rather than the size. This retrospective analysis studied metabolic and morphological response on Positron Emission Tomography (PET) and Computed Tomography (CT), respectively to these agents.
  
  
  METHODS
  Thirty-one patients (23 males, 8 females with an age range of 42-77 years) with Epidermal Growth Factor Receptor (EGFR) positive metastatic lung cancer on Gefitinib, who underwent PET/CT, at baseline and at 4-6 weeks, were assessed by Response Evaluation Criteria In Solid Tumors [RECIST] 1.1 and European Organization for Research and Treatment of Cancer (EORTC) criteria.
  
  
  RESULTS
  Concordance between RECIST 1.1 and EORTC was seen in 26 (83.7%) patients. Discordance was seen in 5 (16.3%) patients. In patients with discordance, the results were confirmed by follow-up imaging. Metabolic EORTC criteria changed the disease status from stable disease to partial response (3 out of 5) and progressive disease (2 out of 5) in these five patients.
  
  
  CONCLUSIONS
  Metabolic criteria using PET/CT could accurately predict response as well as disease progression early in the course of targeted therapy, compared to morphologic criteria. In addition, early metabolic response assessment can predict refractoriness of therapy.
authors.affiliation: Department of Nuclear Medicine and Molecular Imaging, Tata Memorial Hospital, Mumbai, Maharashtra, India.
authors.forename: Ameya D
authors.initials: AD
authors.lastname: Puranik
authors.affiliation: Department of Nuclear Medicine and Molecular Imaging, Tata Memorial Hospital, Mumbai, Maharashtra, India.
authors.forename: Nilendu C
authors.initials: NC
authors.lastname: Purandare
authors.affiliation: Department of Nuclear Medicine and Molecular Imaging, Tata Memorial Hospital, Mumbai, Maharashtra, India.
authors.forename: Sneha
authors.initials: S
authors.lastname: Shah
authors.affiliation: Department of Nuclear Medicine and Molecular Imaging, Tata Memorial Hospital, Mumbai, Maharashtra, India.
authors.forename: Archi
authors.initials: A
authors.lastname: Agrawal
authors.affiliation: Department of Nuclear Medicine and Molecular Imaging, Tata Memorial Hospital, Mumbai, Maharashtra, India.
authors.forename: Venkatesh
authors.initials: V
authors.lastname: Rangarajan
keywords: Computed Tomography; Epidermal growth factor receptor; European organization for research and treatment of cancer; Fluoro-deoxy glucose positron emission tomography; Gefitinib; Lung cancer; Response; Response evaluation criteria in solid tumors