Modern post-operative radiotherapy for stage III non-small cell lung

Charlotte Billiet a,⇑, Herbert Decaluwé b, Stephanie Peeters a, Johan Vansteenkiste c, Christophe Dooms c,

Karin Haustermans a, Paul De Leyn b, Dirk De Ruysscher a

a Radiation Oncology; b Thoracic Surgery and Leuven Lung Cancer Group; and c Respiratory Oncology (Pneumology) and Leuven Lung Cancer Group, University Hospitals Leuven/KU Leuven, Belgium

Background: We hypothesized that modern postoperative radiotherapy (PORT) could decrease local recurrence (LR) and improve overall survival (OS) in patients with stage IIIA-N2 non-small-cell lung cancer(NSCLC).

Methods: To investigate the effect of modern PORT on LR and OS, we identified published phase III trials for PORT and stratified them according to use or non-use of linear accelerators. Non-individual patient data were used to model the potential benefit of modern PORT in stage IIIA-N2 NSCLC treated with induction chemotherapy and resection.

Results: Of the PORT phase III studies, eleven trials (2387 patients) were included for OS analysis and eight (1677 patients) for LR. PORT decreased LR, whether given with cobalt, cobalt and linear accelerators, or with linear accelerators only. An increase in OS was only seen when PORT was given with linear accelerators, along with the most significant effect on LR (relative risk for LR and OS 0.31 (p = 0.01) and 0.76 (p = 0.02) for PORT vs. controls, respectively).

Four trials (357 patients) were suitable to assess LR rates in stage III NSCLC treated with surgery, in most cases after induction chemotherapy. LR as first relapse was 30% (105/357) after 5 years. In the modelling part, PORT with linear accelerators was estimated to reduce LR rates to 10% as first relapse and to increase the absolute 5-year OS by 13%.

Conclusions: This modeling study generates the hypothesis that modern PORT may increase both LR and OS in stage IIIA-N2 NSCLC even in patients being treated with induction chemotherapy and surgery.