All patients recruited divided into two arms：SIB-IMRT or routine IMRT，in the routine arm，the prescription dose was 60Gy/2Gy/30f，and in the SIB arm ，60Gy was given to the field of the tumor and metastatic lymph nodes，50Gy was given to CR lesion and high-risk prevention. The physical advantages of SIB-IMRT are to reduce the radiation dose of organs that are at risk in the lungs, esophagus, and heart ensuring the adequate dose for tumor area at the same time. The investigators are carrying out this trial to compare the efficacy, safety, side effects, and type of failure of the two radiotherapy techniques, which will provide a new choice and reliable basis for the future dose-segmentation study of limited-stage small-cell lung cancer.
Thoracic radiotherapy concurrent with chemotherapy stands for the standard regime for limited staged small cell lung cancer. Involved node radiation（INF） replaced elective node irradiation（ENI） as the more popular since several trails compared the two regimes. simultaneous integrated boost IMRT becomes mature with advancing in IMRT and VMAT. The investigator hypothesis that SIB-IMRT can confine the dose for organs at risk to reduce the toxicities compared with routine IMRT in limited disease small-cell lung cancer.