[Radiation therapy for lung cancer]

Abstract

Radiation therapy is one of the most important modalities for the treatment of lung cancer. Current progress of radiation therapy in cooperation with the development of physics and biology is remarkable. The techniques of three-dimensional treatment planning and three-dimensional conformal radiotherapy (3D-CRT) have facilitated the use of higher radiation doses. Patients with early-stage non-small cell lung cancer (NSCLC) are candidates for curative surgical resection. However, the number of elderly patients has been increasing, and these patients often have medical contraindications that prevent curative surgery. Recently, several clinical trials on stereotactic body radiotherapy (SBRT) using the 3D-CRT technique for solitary lung tumors have been reported. The local control rate for stage I disease is more than 90%, and survival rates are promising. Now a prospective multi-institutional trial is ongoing to determine whether this modality can become a standard treatment for inoperable patients or an alternative to lobetectomy. For locally advanced NSCLC, unfortunately, recent studies have demonstrated that conventional therapies may have reached a therapeutic plateau. Now several radiation dose escalation studies utilizing conventional fractionation and 3D-CRT techniques are ongoing. The strategies of almost all of these trials are to eliminate elective nodal irradiation and deliver a higher dose of radiation to gross tumor volume while sparing normal tissues. Preliminary experience has resulted in promising survival, but should be developed to integrate into the combined treatment to completely control both local disease and other microscopically involved lesions. The combination of novel chemotherapeutic agents and molecular targeting therapies with radiation therapy is being investigated. Development of molecular imaging techniques is expected to facilitate more selective dose escalation in tumors.