Methods: Chemonaive patients with stages IIIB and IV of lung cancer are going to receive Paclitaxel and Cisplatin. Patients will be randomized to receive two cans/day of EPA and DHA containing oral supplement or nutritional assessment one week prior to treatment until completing two cycles. Serum levels of Reactive C Protein (RCP), interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) are going to be measured baseline and after two courses of chemotherapy. Phase angle and body composition will be measured using Bioimpedance analysis (BIA). Quality of life, dietary intake will be assessed with validate questionnaires. All data is going to be collected in a database for further blind analysis. Written informed consent will be collected from all patients.