ESTRO 2020 Abstract Book

S140 ESTRO 2020

PH-0280 Quality of surgery and RT in stage IIIN2 NSCLC: Insights from the Lung Adjuvant Radiotherapy trial Y. Moukasse 1 , N. Pourel 2 , D. Lerouge 3 , C. Faivre-Finn 4 , S. Ramella 5 , J. Edwards 6 , P. Van Schil 7 , R. Rami-Porta 8 , P. Thomas 9 , A. Bardet 10 , C. Le Pechoux 1 1 Gustave Roussy Institute, Radiation Oncology, Villejuif, France ; 2 Sainte Catherine Institute, Radiation Oncology, avignon, France ; 3 François Baclesse Center, Radiation Oncology, Caen, France ; 4 The Christie NHS Foundation Trust, Radiation Oncology, Manchester, United Kingdom ; 5 Campus Bio-Medico University Hospital, Radiation Oncology, Roma, Italy ; 6 Northern General Hospital, Thoracic Surgery, Sheffield, United Kingdom ; 7 University Hospital of Antwerp, Thoracic and Vascular Surgery, Antwerp, Belgium ; 8 Hospital Universitari Mutua Terrassa- and Ciberes Lung Cancer Group, Thoracic Surgery, Terrassa, Spain ; 9 North University Hospital- Aix-Marseille University & Hospitals, Thoracic Surgery, Marseille, France ; 10 Gustave Roussy Institute, Biostatistics, Villejuif, France Purpose or Objective The objective of the phase III Lung Adjuvant Radiotherapy Trial (LungART) is to determine if modern conformal mediastinal postoperative radiotherapy (PORT), adapted to tumor location and involved lymph nodes (LN), can improve disease-free survival (DFS) for completely resected stage III N2 non-small-cell lung cancer (NSCLC) patients (pts). Given the potential toxicity of PORT in older randomized trials, it is crucial to investigate the quality assurance (QA) of both surgery and radiotherapy (RT). Material and Methods First, a surgical advisory committee composed of 4 expert thoracic surgeons reviews anonymized surgical and pathological reports, and establishes the quality of tumor resection and nodal exploration, taking into consideration the international guidelines. Then, for the RT QA analyses, RT advisory committee composed of 4 expert thoracic radiation oncologists, reassesses dosimetric plans of each patient treated in the PORT arm and correlates nodal target coverage with surgical data. Results In June 2019, from 252 patients treated in PORT arm, 142 files have already been analyzed for surgical and RT QA. The basic characteristics are specified in the following table:

EORTC criteria. Other kinds of toxicity possibly attributable to the high dose per fraction were also searched for. Results Ninety-two pts were included from 10.03.2014 to 05.02.2019: 2 did not receive the prescribed RT dose; 70 completed 2 cycles of CHT; 22 (24%) received only one CHT cycle. Median follow-up was 21.5 mths (range 1-65) for all pts and 32 mths (range 6-65) for living pts. There were 13 (14%) cases of grade III and higher acute esophageal toxicity. All but one grade III/IV esophageal toxicities were prolonged duration of >2 weeks. Additionally, there were: grade III acute pneumonitis (3), grade IV infectious complication (1), and grade III late pulmonary toxicity (2). Two toxic deaths occurred within 3 months after treatment completion: fatal hemoptysis (1) and complications of prolonged esophageal toxicity (1). Five other deaths that occurrred within one year after treatment were probably treatment-related: lung abscess (1), fatal hemoptysis - in patients with hemoptysis before RT and pulmonary arteries invasion (2), death from undetermined cause without progression in pts with prior pneumonitis (2). Median overall survival was 38 mths (95%CI:27-49) (fig.1.), median progression free survival was 25 mths (95%CI:12-38) (fig.2).

Conclusion Despite the encouraging survival rates, similar or even better than those observed in the modern series of conventionally fractionated RT-CHT, the observed rate of toxic and probably toxic deaths that occurred within one year after treatment challenges the safety of the routine use of accelerated hypofractionated RT with concomitant full dose CHT.