Thoracic Reirradiation with Stereotactic Body Radiation Therapy (SBRT) for Recurrent Advanced Non-Small Cell Lung Cancer (NSCLC)

Locoregional failure is common among patients with advanced non-small cell lung cancer (NSCLC) treated with definitive chemoradiation +/- immunotherapy, and palliative systemic therapy is the most common treatment for locoregional failure. SBRT with ≤5 fractions have been described for small volume local recurrences, but may not be amenable to recurrences that are large or centrally located near critical structures. The purpose of this study is to evaluate the safety and efficacy of hypofractionated RT with 60 Gy in 8 using SBRT treatment techniques as salvage therapy for local failure for patients with advanced NSCLC previously treated with external beam radiation therapy (EBRT). Between July 2013 and February 2020, 5 patients were re-irradiated with SBRT of 60 Gy in 8 fractions for recurrence in the lung parenchyma after previous EBRT delivered to the same site. Patients with lymph node recurrence were excluded from analysis. Internal target volume (ITV) was created on 4D-CT with +0.5cm uniform margin to create the planning target volume (PTV). LINAC-based SBRT was delivered on non-consecutive days. Toxicity was assessed by CTCAE v5.0. Median follow-up from re-irradiation was 36 months (5.9 – 55.3 months). Median age was 67 years (range, 63 – 80 years), with KPS > 70. Patients were previously treated with a median dose of 60 Gy in median number of 30 fractions (59.4 – 66 Gy in 30 – 33 fractions). Median time to re-irradiation was 15 months (7.3 – 28.6 months). Median re-treated tumor size was 4.8 cm, with median re-treated ITV of 58.3 cc (18.3 – 344.6 cc) and median re-treated PTV of 121.3 cc (44.3 – 506.9 cc). Local control was 100%, and 60% patients remained free of any progression of disease at time of analysis. All patients remain alive at follow-up. One patient experienced grade 3 rib fracture as late toxicity for a chest wall invasive recurrence. Our institutional experience shows that SBRT-like 60 Gy in 8 fractions appears to be a safe and effective means of salvaging recurrent advanced NSCLC that was previously irradiated.Abstract 2415; TablePatient NumberInitial StageTime to re-irradiation (months)ITV of re-irradiation (cc)PTV of re-irradiation (cc)Follow-up after re-irradiation (months)Disease StatusAdditional treatment rendered1IIB, T3 N0 M07.3133.822918.1Locally controlled but metastatic disease in spinePembrolizumab and SBRT to oligometastatic adrenal gland2IIIA, T4 N0 M011.657.9113.655.3No evidence of diseaseNone3Recurrence at suture line after wedge resection for IA128.658.3121.350.3Locally controlled but metastatic disease in bilateral lungs, adrenal, and ribCarboplatin, Pemetrexed, and Pembrolizumab followed by SBRT to 3 oligoprogressive lung metastases and maintenance Pemetrexed/Pembrolizumab4IIIA, T2a N2 M018.3344.6506.936.0No evidence of diseaseNone5IIIB, T3 N2 M015.018.344.35.9No evidence of diseaseNone Open table in a new tab