Baseline characteristics
| Category | Radiation therapy group | Non-radiation therapy group | p-value |
| Patients n | 23 | 23 | |
| Age at diagnosis years | 63 (41–77) | 62 (43–79) | 0.26 |
| Females | 13 (57) | 15 (65.1) | 0.14 |
| Smoking history | 18 (90) | 19 (95) | 0.26 |
| Smoking pack-years | 43.2±23.4 | 44.5±21.6 | 0.85 |
| Body mass index kg·m−2 | 25.6±4.9 | 25.8±5.4 | 0.86 |
| Serum LDH U·L−1 | 264.8±64.4 | 380.5±80.1 | 0.08 |
| FEV1 % pred | 76.75±24.4 | 61.4±27.9 | 0.10 |
| FVC % | 87.4±21.3 | 92.5±12.5 | 0.72 |
| Lung disease on CT scan | 0.89 | ||
| Emphysema | 14 (60.9) | 12 (52.2) | |
| Interstitial lung disease | 2 (8.7) | 1 (4.3) | |
| Bronchiectasis | 0 | 0 | |
| Histology of tumour | |||
| Adenocarcinoma | 16 (69.6) | 16 (69.6) | |
| Squamous cell carcinoma | 7 (30.4) | 7 (30.4) | |
| Stage at the time of inclusion# | 0.75 | ||
| Stage IV | 19 (82.6) | 21 (91.3) | |
| Stage IIIB | 4 (17.4) | 2 (8.7) | |
| Previous chemotherapy cycles | 6 (1–18) | 4 (2–10) | 0.11 |
| Lines of chemotherapy prior to nivolumab | 1 (1–3) | 1 (1–3) | |
| Previous chemotherapy | 0.59 | ||
| Carboplatin | 22 (95.7) | 22 (95.7) | |
| Cisplatin | 1 (4.4) | 1 (4.4) | |
| Gemcitabine | 12 (52.2) | 19 (82.6) | |
| Paclitaxel | 14 (90.9) | 4 (17.4) | |
| Vinorelbine | 1 (4.4) | 1 (4.4) | |
| Pemetrexed | 2 (8.7) | 3 (13.0) | |
| Previous radiation therapy | |||
| Thoracic | 23 (100) | ||
| Extrathoracic | 4 (17.4) | ||
| Previous radiation therapy intent | |||
| Previous definitive concurrent chemoradiation | 18 (78.3) | ||
| Previous palliative radiotherapy | 5 (21.7) | ||
| ECOG score at the start of nivolumab | 2 (1–2) | 2 (1–2) | |
| Nivolumab cycles | 9 (1–47)* | 5 (1–34)* | 0.01 |
Data are presented as median (range), mean±sd or n (%), unless otherwise stated. LDH: lactate dehydrogenase; FEV1: forced expiratory volume in 1 s; % pred: % predicted; FVC: forced vital capacity; CT: computed tomography; ECOG: Eastern Cooperative Oncology Group performance status score. #: stage of non-small cell lung cancer prior to initiation of nivolumab was based on the seventh Tumour, Node, Metastasis classification of lung cancer. *: p<0.05.