PROGNOSTIC VALUE OF PET/CT IN LUNG CANCER. RETROSPECTIVE ANALYSIS OF 47 PATIENTS Background: PET/CT (Positron emission tomography/computed tomography) is a hybrid image modality widely used in oncology, for staging, therapy evaluation or follow up. Aim: To evaluate the prognostic value of PET/CT in lung cancer. Material and methods: Retrospective review of PET/CT records, selecting 51 patients with a lung malignancy, mass or nodule referred for PET/CT between December 2008 and December 2010.  All had pathological confirmation of malignancy and had not been treated previously. Age, gender, body mass index, radiological features of lung tumor and metastases, and lung tumor 18F-fluoro-2-deoxy-d-glucose uptake using the SUV (Standardized uptake value) index were recorded. Survival was analyzed using Kaplan-Meier curves and a Cox proportional regression analysis. Results: Pathology confirmed the presence of lung cancer in 47 patients aged 30 to 88 years. Four patients (7.8%) had other type of tumors such as carcinoid or lymphoma. Fifty percent of lung cancer patients died during a mean observation lapse of 18 months (range: 2-34 months). Patients with metastases, local lymph node involvement, a lung tumor size ? 3 cm and high tumor uptake (SUVmax > 6) had significantly lower survival.  Occurrence of metastases was the only independent prognostic factor in the Cox regression. A lung lesion with a SUVmax ? 12 was always associated to hilar/mediastinal lymph node involvement. Conclusions: PET/CT imaging gives important prognostic information in lung cancer patients.