PURPOSE: To evaluate feasibility and efficacy of concomitant radiochemotherapy (CRCT) in Stage IIIB nonsmall-cell lung cancer (NSCLC), two induction chemotherapy cycles combining etoposide and carboplatin were first delivered, followed by CRCT with daily radiation fraction in association with carboplatin. METHODS AND MATERIALS: Forty patients with biopsy-proven, locally advanced unresectable nonmetastatic NSCLC were enrolled. Induction chemotherapy consisted of two cycles (day 1 and day 28) of etoposide (VP16:100 mg/m2, days 1 to 3) and carboplatin (CBDCA:350 mg/m2, day 1). Irradiation starting at day 56, delivered 66 Gy in 2 Gy daily fraction, 5 days a week, along with a daily dose of CBDCA (15 mg/m2) given intravenously 2 to 4 h before radiation. In nonprogressive patients under induction chemotherapy, two additional cycles of VP16-CBDCA were administered 4 weeks after the completion of CRCT. RESULTS: Out of the 40 patients enrolled (38 males, 2 females), 37 (93%) received induction chemotherapy as scheduled, with 38% Grade 3-4 hematological toxicity. Response rate to induction chemotherapy was 11% (4/37). No tumor became resectable. CRCT was delivered to 32 of these 37 patients, with full doses given to 91% of them. Clinical and hematological Grade 3-4 toxicity rates were 21 and 13%, respectively. Additional chemotherapy was delivered in 12 of 26 nonprogressive patients. At final evaluation, performed 3 months after the end of CRCT, 38% of 26 evaluable patients were responders (4 complete and 6 partial), leading to a 25% (10 of 40) overall objective response rate. Of these 10 responders, 8 became responders after CRCT only. Overall, the 1-year local control rate was 28% (11 of 40). The median survival time was 9 months and the 1-year and 2-year overall survival rates were 38 and 15%, respectively. Thirty-six patients died from local progression (25 patients), distant metastasis (9 patients), or pulmonary fibrosis (2 patients). CONCLUSION: Concomitant CRCT with CBDCA is feasible with acceptable induction chemotherapy-related toxicity and a 1-year local control rate of 28%. Response rate to induction chemotherapy was low and better chemotherapy combination should be used to reduce distant failure probability and to improve local response rate before CRCT.