P2.05-015 Long-Term Outcomes of Prospective Phase П Clinical Trial for Stereotactic Ablation Radiotherapy in Recurrent NSCLC: Topic: Clinical Outcome

Abstract

To evaluate the long-term efficacy, pattern of failure, and toxicity of stereotactic ablative radiotherapy (SABR) for recurrent or multiple primary non-small-cell lung cancer (NSCLC). Patients with histologically confirmed, 18F-fluorodeoxyglucose (18F-FDG)-PET staged, recurrent or multiple primary NSCLC, suitable for SABR (<5 cm, not abutting critical structures, met with SABR dose volume constraints), were prospectively enrolled and treated with volumetric image-guided SABR to 50 Gy in 4 fractions (prescribed to planning target volume). Lobar recurrent disease was defined as recurrence in the same lobe with the same histology after definitive therapy from prior NSCLC (n=9); recurrent or oligo-metastatic disease (<3 lesions) was defined as recurrence with same histology within four years in different lobe (n=35). Multiple primary NSCLC was defined as secondary NSCLC with either different histology, or same histology but located in the different lobe with more than 4 years after initial definitive treatment of prior NSCLC (n=16); synchronous tumors was defined as with two early stage NSCLC in the different side (n=3). Four-dimensional computed tomography (4DCT) was used for simulation and planning. Patients were followed with CT or PET/CT every three months for two years, then every 6 months for three years and then annually. From February 2006 to April 2013, 63 patients were enrolled and eligible for evaluation. The median age was 70 years (range 45-86) and median follow-up was 4.2 years (the interquartile range 3.0-7.3 years). A total of 5 (7.9%) patients developed cumulative actual local recurrence within PTV and 18 patients (28.6%) developed any cumulative actual recurrence (local, regional and distant) after SABR. Estimated total local failure rates in the same lobe at 3-, 5-year were both 11.2% (95% CI 6.8-15.6). Estimated 3-, 5-year PFS rates were 60.2% (95% CI 53.7-66.7) and 52.6% (95% CI 43.5-61.7), respectively; corresponding overall survival rates were 64.1% (95% CI 58.0-70.2) and 52.9% (95% CI 45.5-60.3). Three (4.8%) patients developed grade 3 treatment-related adverse events (one [1.6%] dermatitis, one [1.6%] chest wall pain, and one [1.6%] radiation pneumonitis). No patient had grade 4 or 5 event. This exploratory prospective study showed excellent 5 years local control, minimal toxicity and outstanding 5 years OS and PFS for recurrent or multiple primary NSCLC treated with SABR, indicating a potential cure for some patients. Close follow up and surveillance after initial definitive treatment should be considered to detect early recurrence in NSCLC.