Postoperative Radiotherapy for Lung Cancer: Improvement in Locoregional Control Using Three-Dimensional Compared With Two-Dimensional Technique

Purpose: To determine whether lung cancer patients treated with three-dimensional (3D) postoperative radiotherapy (PORT) have more favorable outcomes than those treated with two-dimensional (2D) PORT. Patients and Methods: We retrospectively analyzed the charts of 153 lung cancer patients who underwent PORT with curative intent at our center between 1995 and 2007. The patients were grouped according to the RT technique; 66 patients were in the 2D group and 87 in the 3D group. The outcomes included locoregional control, survival, and secondary effects. All patients were treated using a linear accelerator at a total dose of approximately 50 Gy and 2 Gy/fraction. A few patients (21%) also received chemotherapy. Most tumors were in the advanced stage, either Stage II (30%) or Stage III (65%). The main clinical indications for PORT were positive resection margins (23%) and Stage pN2 (52%) and pN1 (22%). The patient characteristics were comparable in both groups. Results: Kaplan-Meier analysis showed that the 3D technique significantly improved the locoregional control rate at 5 years compared with the 2D technique (81% vs. 56%, p = .007 [Cox]). The 2D technique was associated with a more than twofold increased risk of locoregional recurrence (hazard ratio, 2.7; 95% confidence interval, 1.3-5.5; p = .006). The overall survival rate did not differ at 5 years (38% vs. 20%, p = .3 [Cox]). The toxicities were also similar and acceptable in both groups. Conclusion: The 3D technique for conformal PORT for lung cancer improved the locoregional control rates of patients compared with the 2D technique.