The Regression Pattern of Primary Lesions in Lung Cancer After Definitive Radiotherapy

Inclusion Criteria: 1. Age ≥18 years old; 2. Stage II-III lung cancer with a clear pathological diagnosis report or medical record, not undergoing surgery before radiotherapy; 3. The primary lung lesion received definitive radiotherapy (defined as conventional fractionation radiotherapy with dose ≥50Gy, stereotactic radiotherapy with biologically effective dose ≥100Gy); 4. The target lesion of the lung receiving radiotherapy can be measured; 5. Imaging data can be obtained before and after radiotherapy; 6. Complete radiotherapy as planned, or the actual received dose has reached the defined definitive dose. Exclusion Criteria： 1. Before radiotherapy, the primary lesion of the lung had received local treatment such as surgery or ablative treatment; 2. The radiotherapy plan was not completed, and the actual dose received did not reach the definitive dose (defined as conventional fractionation radiotherapy with dose \<50Gy, stereotactic radiotherapy with biologically effective dose \<100Gy)； 3. Required imaging data cannot be obtained; 4. Other conditions considered by the investigator to be inappropriate for enrollment.