[Radiation therapy in the treatment of lung cancer]

Although non-small cell lung cancer (NSCLC) has the potential for cure with surgical resection, unfortunately less than 15% of all patients and less than 25% of those who present with intrathoracic localized disease are candidates for curative surgical resection. Elderly patients, even if they have resectable disease, often have medical contraindications to surgery, such as cardiovascular disease or pulmonary dysfunction. Radiation therapy (RT) for lung cancer has been practiced as (1) curative thoracic irradiation for inoperable or unresectable NSCLC, (2) preoperative and postoperative irradiation, (3) thoracic irradiation for limited-stage small cell lung cancer(SCLC), (4) prophylactic cranial irradiation (PCI) for SCLC, and (5) palliative irradiation for more advanced disease. Recent evidence indicates that RT with high equivalent doses of 60 Gy or more using conventional once daily fractionation may improve the survival rate for patients with locally advanced unresectable NSCLC when combined with cisplatin-based chemotherapy or administered by altered fractionation. In limited-stage SCLC, the additions of thoracic RT and prophylactic cranial irradiation to systemic chemotherapy have also improved disease control. In patients with more advanced disease, RT has provided relief of symptoms. Newer radiotherapeutic methods are expected to hold promise in increasing the dose to tumor while sparing normal tissue. Recently, heavy ion charged particle therapy, brachytherapy, stereotactic irradiation, and multi-daily fractionation have shown promise in the treatment of lung cancer. Furthermore, there have been advances in the technology for treatment delivery, especially three-dimensional treatment planning systems, patient fixation tools, and respiration synchronous systems for RT.