To Örebro University

Background: Concurrent chemoradiotherapy is the mainstay treatment for NSCLC stage III disease, however, with a rather high probability of locoregional and metastatic recurrence further treatment optimization is warranted. Based on previous one-armed trials with dose escalated radiotherapy, showing feasibility, the Swedish Lung Cancer Study Group aimed to investigate whether dose escalation based on individual normal tissue constraints could improve outcome in this randomized phase II trial.

Method: NSCLC patients with stage III disease, good performance status (0-1), adequate lung function (FEV1 > 1.0 L and CO diff. > 40%) received three cycles of cisplatin (75 mg/m2 day 1) and vinorelbine (25 mg/m2 day 1 and 8) every third week. The radiotherapy started concurrently with the second cycle, with either 2 Gy daily, 5 days a week, to a total dose of 68 Gy (standard arm A) or escalated therapy (B) based on constraints to the spinal cord, esophagus and lungs up to 84 Gy by adding an extra fraction of 2 Gy per week while keeping the total treatment time constant at seven weeks with the same dose to involved nodes and primary tumor.

Result: A pre-planned safety analysis revealed excessive toxicity and decreased survival in the escalated arm, and the study was stopped. Thirty-six patients were included during 2011-2013 (56% male, 78% with adenocarcinoma, 64% with PS 0 and 53% with stage IIIB). The median progression-free survival (PFS) and overall survival (OS) were 11 and 17 months in the dose escalated group compared to 28 and 45 months in the standard group. The 1-, 3- and 5-year survival rates were 56%, 33% and 17% in the escalated arm and 72%, 61% and 34% in the standard arm. There were four toxicity-related deaths due to esophageal perforations (one in arm A and three in arm B) and three deaths due to pneumonitis (one in arm A and two in arm B).

Conclusion: Dose-escalated concurrent chemoradiotherapy to 84 Gy to primary tumor and nodal disease is hazardous, with a high risk of excessive toxicity, whereas modern standard dose chemoradiotherapy with proper staging given in the control arm shows a promising outcome with a median survival of 45 months and a 5-year survival of 34%. A possible step forward will be to improve systemic therapy, but future approaches with escalated radiotherapy may include boost techniques to remaining PET positive areas or different escalation schedules to the primary tumor and mediastinal nodes.