Safety and Efficacy of SBRT in the Reirradiation for Ultra-central Thoracic Malignant Tumors

The reirradiation of thoracic tumor is difficult. The possibility of surgery or re course radiotherapy is very small. In the NCCN guideline, only systemic treatment is recommended. However, the effective rate of systemic treatment is low. SBRT has the characteristics of high dose in tumor target area and low dose in surrounding normal tissues. In theory, SBRT is more conducive to the protection of normal tissues and can potentially be used in the salvage treatment of recurrent lesions after radiotherapy. Even so, SBRT is still controversial in the rescue treatment of recurrent lung cancer after radiotherapy, especially for "ultral-central" lesions close to mediastinal structures (such as bronchus, esophagus and large blood vessels), which have a high probability of fatal side effects. However, a few studies on the application of SBRT in the reirradiation for ultral-central lung cancer have shown acceptable safety and efficacy. Generally speaking, there are few studies on SBRT in the treatment of recurrent ultral-central tumor with limited data. The purpose of this study is to further evaluate the efficacy and toxicities of SBRT in the treatment of recurrent ultral-central tumors after radiotherapy.