This randomized controlled non-inferior trial prospectively enrolled patients with limited-stage small cell lung cancer (LS-SCLC). Patients in the experimental group would receive radiotherapy with omission of the clinical target volume (CTV) for the primary tumor, while those in the control group would receive radiotherapy including CTV. The efficacy and toxicity of the two groups are compared to provide evidence for the radiotherapy of LS-SCLC. The target volume of LS-SCLC may be reduced by omitting CTV without increasing local recurrence but potentially reducing the dose to organs at risk a