Re-Irradiation for Locally Recurrent Lung Cancer: A Single Center Retrospective Analysis

The treatment of locally recurrent lung cancer is a major challenge for radiation-oncologists, especially with data on high-dose reirradiation being limited to small retrospective studies. The aim of the present study is to assess overall survival (OS) for patients with locally recurrent lung cancer after high-dose thoracic reirradiation. Thirty-nine patients who were re-irradiated for lung cancer relapse between October 2013 and February 2019 were eligible for the current retrospective analysis. All patients were re-irradiated with curative intent for in-field tumor recurrence. The diagnostic work-up included a mandatory ¹⁸F-FDG-PET-CT scan and-if possible-histological verification. The ECOG was ≤2, and the interval between initial and second radiation was at least nine months. Thirty patients (77%) had non-small cell lung cancer (NSCLC), eight (20%) had small cell lung cancer (SCLC), and in one patient (3%) histological confirmation could not be obtained. More than half of the patients (20/39, 51%) received re-treatment with dose differentiated accelerated re-irradiation (DART) at a median interval of 20.5 months (range: 6-145.3 months) after the initial radiation course. A cumulative EQD₂ of 131 Gy (range: 77-211 Gy) in a median PTV of 46 mL (range: 4-541 mL) was delivered. Patients with SCLC had a 3 mL larger median re-irradiation volume (48 mL, range: 9-541) compared to NSCLC patients (45 mL, range: 4-239). The median cumulative EQD2 delivered in SCLC patients was 84 Gy (range: 77-193 Gy), while NSCLC patients received a median cumulative EQD2 of 135 Gy (range: 98-211 Gy). The median OS was 18.4 months (range: 0.6-64 months), with tumor volume being the only predictor (p < 0.000; HR 1.007; 95%-CI: 1.003-1.012). In terms of toxicity, 17.9% acute and 2.6% late side effects were observed, with a toxicity grade >3 occurring in only one patient. Thoracic high dose reirradiation plays a significant role in prolonging survival, especially in patients with small tumor volume at recurrence.