Intensity-modulated Radiotherapy (IMRT) With Simultaneous Integrated Boost (SIB) for Inoperable Non-small-cell Lung Cancer

Lung cancer is one of the most common cancer and the leading causes of cancer death in patients worldwide. Approximately 80% of NSCLC were inoperable. Concurrent chemo-radiation therapy (CCRT) is a standard treatment for locally advanced NSCLC who are not candidates for surgery. Nevertheless, the prognosis of patients with locally advanced NSCLC (LA-NSCLC) is still poor. Local control (LC) after CCRT is one of the most important prognostic factors. Local failure is common after standard-dose chemoradiation for NSCLC. Studies of stereotactic body radiation therapy (SBRT) have shown a steep dose response in treating early-stage lung cancer. Improving the total dose and shortening the overall treatment time may be effective for improving the LC rates. However, problems remain due to the toxicity to adjacent critical structures (e.g,lung,heart, esophagus), the target volumes usually limits the doses escalated that cannot be safely delivered by conventional radiotherapy techniques. In order to avoid the acute and late radiation toxicity of normal tissues, different dose prescriptions can be delivered to different target volumes in the same fraction, which deliver a higher dose to the Gross Tumor Volume (GTV) and a relatively lower dose to the subclinical disease. The technique is called simultaneous integrated boost intensity modulated radiotherapy (SIB-IMRT). Investigators hypothesized that use of SIB-IMRT technology can safety increasing the radiation dose and benefit for inoperable NSCLC patients.