Local control and toxicity for centrally located NSCLC: SABR in no fly zone

Purpose or Objective: Only few experiences had investigated the use of SABR for locally advanced NSCL centrally located. The RTOG 0236 Trial warns about the risks of SBRT in NSCLS located within 2 cm of the bronchial tree, the edophagus, heart and pericardium. The aim of this study is to evaluate the use of hypofracionated ablative radiotherapy in this setting of disease in terms of local control, toxicities and overall survival (OS). Material and Methods: Between Jun 2011 and March 2015 36 patients (pts) were treated with Hypofrationated Image guided-Volumetric Modulated Arc Therapy (IGRT-VMA T) for centrally located NSCLC stage III-IV or centrally recurrent NSCLC biopsy-proven. Target was contoured using volumetric mdc enhanced CT and PET/CT scan and OAR according RTOG 0236 Trial criteria. Dose Constraints used were: Single lung V10<20%, Dmax bronchus 38 Gy, Dmax esophagus 35 Gy, Spinal Cord 22.5 Gy, Heart and pericardium 38 Gy. The dose was prescribed to 80% isodose. The VMAT treatment was delivered by 6MV beam modulator Linac with 4 mm MLC and in breath hold using ABC device. Patient set-up and isocenter position was controlled before each fraction by CBCT . T arget volume ranged from 21 to 150 cm3 (median 49.5). Median delivered dose was 40 Gy/5fx (median BED 10 of 100 Gy). Toxicities were assessed by CTCAE 4.0 criteria and the response was evaluated 2 months after the end of SBRT and every 4 month successively by CT and PET/CT. Results: Median follow-up was 18 months (range 3 – 45). 25 pts are still alive (69.5%) and 8 of them have NED. 19/36 (52.8%) of treated lesions show complete respons and 10 (27.7%) partial response. Local control was 89% at 12 months and 67% at 18 months. OS was 84% and 73% at 12 and 18 months respectively. Acute toxicity worse than G2 was observed only in 1 pt. Late toxicity G3 was observed in 3 pts (esophageal stenosis in 1 case and bronco-esophageal fistula in 2 pts). Both fistulas occour in the same site of local recurrence Conclusion: In our experience hypofractionated treatment with ablative dose for NSCLC locate in “no fly zone” is safe if dose constraints for OAR are respected. The two major late toxicities observed occurred in the same site of local recurrence. The treatments with BED 10 values of 100 Gy or more are effective leading to LC rate of 89% and 67% at 12 and 18 month respectlively. Although OS is not the primary endpoint of this study, beacuse include also metastatic and recurrent disease, nevertheless shows interesting values (84% at 12 months and 73% at 18 months)