In order to assess the development of treatments and the curability of SCLC, we analyzed a total of 181 patients entered in our protocol studies since 1976. Between 1976 and 1981, 37 patients (20 LD and 17 ED) were treated with COMP, a 4-drug combination of cyclophosphamide (CTX), vincristine (VCR), methotrexate, and procarbazine. During the period, chest irradiation (RT) was administered optionally to those with LD. Between 1981 and 1986, 112 patients (56 each of LD and ED) were treated with a cyclic alternating chemotherapy of the COMP and VAN, a 3-drug combination of etoposide (VP-16), adriamycin (ADM), and nimustine. In this study, we randomized LD patients either to receive CT alone or CT plus chest RT of 40 Gy to assess the role of chest RT in the treatment of patients in LD. Complete responders were also randomized either to receive prophylactic cranial irradiation (PCI) or not. Thereafter, a pilot phase II study of a hybrid regimen has been conducted in 32 patients (16 each of LD and ED), in which CTX, ADM and VCR (CAV) was given on day 1, and cisplatine and VP-16 (PVP) on days 8 and 9. Chest RT was administered mandatory to LD in this study. The median survival time (MST) has been prolonged with an improvement in response rate over CT in both LD and ED: MST of LD was 10 months for COMP, 14 months for COMP-VAN, and not achieved for CAV-PVP hybrid regimen (13 of 16 patients alive between 10 and months), while that of ED was 8 months for COMP, 11 months for COMP-VAN, and 13 months for CAV-PVP hybrid regimen. The randomized study comparing CT alone and CT plus chest RT revealed that chest RT played a substantial, but not significant, for long survival in LD. Finally 13 of 149 patients treated between 1976 and 1986 were long-term, disease-free survivors beyond 2 years (12 LD and 1 ED). Two of them who had not received PCI had a relapse in the brain, but the remaining 11 patients are alive and disease-free between 28 and 84 months. These results imply that SCLC is potentially curable, but it will be difficult to achieve a cure in a substantial proportion of patients with the disease.