Characteristics of the study population by case–control status and sex
| Study participants’ characteristics | Male n (%) | P value* | Female n (%) | P value* | ||
| Cases 501 (17.3) | Controls 2398 (82.7) | Cases 157 (12.7) | Controls 1079 (87.3) | |||
| Age categories, years | N (%) | N (%) | <0.001 | N (%) | N | 0.070 |
| <40 | 12 (2.4) | 204 (8.5) | 8 (5.1) | 114 (10.6) | ||
| 40–44 | 16 (3.2) | 95 (3.9) | 6 (3.8) | 73 (6.8) | ||
| 45–49 | 38 (7.6) | 222 (9.2) | 14 (8.9) | 108 (10.0) | ||
| 50–54 | 58 (11.6) | 325 (13.5) | 22 (14.0) | 149 (13.8) | ||
| 55–59 | 106 (21.1) | 423 (17.6) | 24 (15.3) | 173 (16.0) | ||
| 60–64 | 103 (20.6) | 430 (17.9) | 22 (14.0) | 184 (17.0) | ||
| 65–69 | 77 (15.4) | 331 (13.8) | 32 (20.4) | 147 (13.6) | ||
| 70–74 | 46 (9.2) | 206 (8.6) | 15 (9.5) | 83 (7.7) | ||
| 75–79 | 27 (5.4) | 99 (4.1) | 7 (4.5) | 26 (2.4) | ||
| 80–84 | 17 (3.4) | 47 (1.2) | 3 (1.2) | 15 (1.4) | ||
| 85+ | 1 (0.2) | 16 (0.7) | 4 (2.5) | 7 (0.6) | ||
| Cigarette smoking status | <0.001 | 0.216 | ||||
| Never smokers | 103 (20.6) | 1442 (60.1) | 146 (93.0) | 1036 (96.0) | ||
| Current smokers | 212 (42.3) | 440 (18.4) | 5 (3.2) | 18 (1.7) | ||
| Former smokers | 186 (37.1) | 515 (21.5) | 6 (3.8) | 25 (2.3) | ||
| Intensity of smoking (pack/year) in ever smokers | <0.001 | 0.026 | ||||
| <10 | 55 (11) | 359 (15.0) | 4 (2.5) | 27 (2.5) | ||
| 10–20 | 48 (9.6) | 167 (7.0) | 4 (2.5) | 5 (0.5) | ||
| >20 | 295 (58.9) | 430 (17.9) | 3 (1.9) | 11 (1.0) | ||
| Opium consumption status (times/day) | <0.001 | <0.001 | ||||
| Never | 213 (42.5) | 1970 (82.1) | 133 (84.7) | 1056 (97.8) | ||
| <1/day | 103 (20.6) | 295 (12.3) | 5 (3.2) | 19 (1.8) | ||
| 1–2/day | 120 (23.9) | 99 (4.1) | 11 (7.0) | 2 (0.2) | ||
| >2/day | 65 (13.0) | 34 (1.4) | 8 (5.1) | 2 (0.2) | ||
| Waterpipe smoking | 0.024 | <0.001 | ||||
| Never | 455 (90.8) | 2245 (93.6) | 127 (80.9) | 993 (92.0) | ||
| Ever | 46 (9.2) | 153 (6.4) | 30 (19.1) | 86 (8.0) | ||
| Environmental tobacco smoke | 0.047 | <0.001 | ||||
| Never | 317 (63.3) | 1752 (73.1) | 88 (56.1) | 693 (64.2) | ||
| Ever | 184 (36.7) | 646 (26.9) | 69 (43.9) | 386 (35.8) | ||
| Respiratory disease history | <0.001 | <0.001 | ||||
| Never | 451 (90.0) | 2259 (94.2) | 131 (83.4) | 1026 (95.1) | ||
| Ever | 50 (10.0) | 139 (5.8) | 26 (16.6) | 53 (4.9) | ||
| Histopathology classification | ||||||
| Epithelial tumours | ||||||
| Adenocarcinoma | 168 (33.5) | 81 (51.6) | ||||
| Squamous cell carcinoma | 148 (29.5) | 28 (17.8) | ||||
| Neuroendocrine tumours | 99 (19.7) | 15 (9.5) | ||||
| Other epithelial neoplasm | 57 (11.4) | 21 (13.4) | ||||
| Non-epithelial tumours | 15 (3.0) | 7 (4.5) | ||||
| Missing | 14 (2.8) | 5 (3.2) | ||||
| The longest occupation held (major groups of ISCO-68) | <0.001 | 0.6 | ||||
| 0/1: Professional, technical and related workers | 31 (6.2) | 266 (11.1) | 7 (4.5) | 53 (4.9) | ||
| 2: Administrative and managerial workers | 4 (0.8) | 61 (2.5) | 2 (1.3) | 10 (0.9) | ||
| 3: Clerical and related workers | 27 (5.4) | 212 (8.8) | 2 (1.3) | 16 (1.4) | ||
| 4: Sales workers | 38 (7.6) | 181 (7.5) | 0 (0.0) | 11 (1.0) | ||
| 5: Service workers | 22 (4.4) | 125 (5.2) | 0 (0.0) | 32 (3.0) | ||
| 6: Agricultural, animal husbandry and forest | 140 (27.9) | 541 (22.6) | 8 (5.1) | 58 (5.4) | ||
| 7: Craft and related trades workers | 29 (5.6) | 147 (6.1) | 6 (3.8) | 39 (3.6) | ||
| 8: Plant and machine operators | 48 (9.6) | 172 (7.2) | 0 (0.0) | 1 (0.1) | ||
| 9: Elementary occupations | 152 (30.3) | 554 (23.1) | 1 (0.6) | 4 (0.4) | ||
| X: Military force | 9 (1.8) | 130 (5.4) | – | – | ||
| X1: Housewives | – | – | 131 (83.4) | 849 (78.7) | ||
| Missing, students, jobless | 1 (0.2) | 9 (04) | 0 (0.0) | 6 (0.5) | ||
*P value calculated using the χ2 test.
–, no data; ISCO-68, International Standard Classification of Occupations.