Radiation therapy in the management of limited small cell lung cancer: When, where, and how much?

Progress in the treatment of patients with small cell lung cancer (SCLC) has come in two phases. In the first phase, SCLC was recognized, even when seemingly localized to the lung and intrathoracic lymph nodes, to be widely metastatic and to require effective systemic therapy from the outset. The development of active chemotherapeutic agents and combinations in the 1970s improved median survival from the 6 months seen with radiotherapy alone to about 1 year. In the second phase has come the recognition that local control of a disease, even one with systemic spread, is necessary for its cure. This has resulted both in a better appreciation of the role of radiation therapy in SCLC treatment and in efforts to optimize combined-modality regimens using radiotherapy and chemotherapy. With current treatment regimens involving concurrent or closely interdigitated administration of cisplatin and etoposide chemotherapy and radiation doses of 45 Gy given over 3 to 5 weeks, median survivals of 20 to 24 months have been reported by many single institutions and confirmed in large cooperative group trials. Issues remaining to be resolved include optimization of radiation dose, volume, and timing; the role of prophylactic cranial irradiation; and how to reduce acute and late toxic reactions of treatment. As we develop more specific therapies based on specific molecular and biological characteristics of SCLC, including its autocrine growth regulation, we will be challenged to integrate these successfully with current radiation and chemotherapeutic approaches.