| Characteristics | All patients | Cases with EGFR mutations | Control cases |
| Subjects | 69 (100) | 17 (24.6) | 52 (75.4) |
| Sex | |||
| Male | 37 (53.6) | 6 (35.3) | 31 (59.6) |
| Female | 32 (46.4) | 11 (64.7) | 21 (40.4) |
| Age yrs | 55 (26–81) | 56 (26–70) | 55 (39–81) |
| Smoking history | |||
| Never-smokers | 22 (32.0) | 11 (64.7) | 11 (21.2) |
| Former or current smokers | 47 (68.0) | 6 (35.3) | 41 (78.8) |
| Histology | |||
| Adenocarcinoma | 47 (68.0) | 14 (82.4) | 33 (63.5) |
| Large-cell carcinoma | 15 (21.7) | 2 (11.8) | 13 (25.0) |
| Bronchioloalveolar carcinoma | 1 (1.5) | 1 (5.8) | 0 |
| Squamous cell carcinoma | 6 (8.7) | 0 | 6 (11.5) |
| ECOG PS | |||
| 0 | 9 (13.0) | 1 (5.8) | 8 (16.3) |
| 1 | 40 (58.0) | 10 (58.8) | 30 (61.2) |
| 2 | 14 (20.2) | 5 (29.4) | 9 (18.4) |
| 3 | 2 (2.9) | 0 | 2 (4.1) |
| Unknown | 4 (5.8) | 1 (5.8) | 3 (5.7) |
| Erlotinib treatment line | |||
| 1st | 26 (37.7) | 10 (58.8) | 16 (30.8) |
| 2nd | 20 (29.0) | 5 (29.4) | 15 (28.8) |
| 3rd | 23 (33.3) | 2 (11.8) | 21 (40.4) |
| Extracranial metastases | |||
| Yes | 45 (65.2) | 10 (58.8) | 35 (67.3) |
| No | 24 (34.8) | 7 (41.2) | 17 (32.7) |
| WBRT | |||
| No | 8 (11.6) | 8 (47.1) | 0 |
| Yes | 55 (79.8) | 9 (52.9) | 46 (88.4) |
| Unknown | 6 (8.7) | 0 | 6 (11.6) |
| Post-erlotinib chemotherapy | |||
| Yes | 32 (46.4) | 9 (52.9) | 23 (44.2) |
| No | 37 (53.6) | 8 (47.1) | 29 (55.8) |
| EGFR mutation | |||
| Exon 19 deletion | 12 (17.4) | 12 (70.6) | |
| Exon 21 L858R | 5 (7.2) | 5 (29.4) |
Data are presented as n (%) or median (range). Data for the entire series, for those patients harbouring an EGFR gene mutation and for control cases are shown. EGFR: epidermal growth factor receptor; ECOG PS: Eastern Cooperative Oncology Group performance status; WBRT: whole brain radiotherapy.