| Case, n(%) | Control, n(%) |  | ||||
---|---|---|---|---|---|---|---|
 | Smokers | Never smokers | Total | Smokers | Never smokers | Total | p valuea |
Total | 289 | 156 | 445 | 482 | 466 | 948 | Â |
Gender | Â | Â | Â | Â | Â | Â | Â |
   Male | 163 (56) | 46 (30) | 209 (47) | 241 (50) | 145 (31) | 386 (41) | p = 0.03 |
   Female | 126 (44) | 110 (70) | 236 (53) | 241 (50) | 321 (69) | 562 (59) |  |
Age | Â | Â | Â | Â | Â | Â | Â |
   < 35 | 1 (< 1) | 10 (6) | 11 (3) | 58 (12) | 86 (18) | 144 (15) |  |
   35-45 | 9 (3) | 21 (13) | 30 (7) | 77 (16) | 89 (19) | 166 (180 |  |
   45-55 | 34 (12) | 27 (17) | 61 (14) | 88 (18) | 85 (18) | 173 (18) |  |
   55-65 | 63 (22) | 28 (18) | 91 (20) | 101 (21) | 88 (19) | 189 (20) |  |
   65-75 | 131 (45) | 57 (37) | 188 (42) | 100 (21) | 71 (15) | 170 (18) |  |
   > 75 | 51 (18) | 13 (8) | 64 (14) | 58 (12) | 48 (10) | 106 (11) |  |
Age, Mean ± SD | 66 ± 10 | 59 ± 13 | 64 ± 12 | 56 ± 16 | 53 ± 17 | 54 ± 16 | < .0001 |
Ethnicity | Â | Â | Â | Â | Â | Â | Â |
   White | 255 (88) | 97 (62) | 352 (79) | 429 (89) | 346 (74) | 775 (82) | p = 0.07 |
   Asian | 21 (7) | 48 (31) | 69 (16) | 27 (6) | 78 (17) | 105 (11) |  |
   Other | 13 (5) | 11 (7) | 24 (5) | 26 (5) | 42 (9) | 68 (7) |  |
Education | Â | Â | Â | Â | Â | Â | Â |
   < 8 years | 97 (34) | 36 (23) | 137 (31) | 55 (11) | 68 (15) | 140 (15) | < .0001 |
   8-11 years | 137 (47) | 52 (33) | 189 (42) | 212 (44) | 187 (40) | 399 (42) |  |
   ≥12 years | 55 (19) | 64 (41) | 119 (27) | 205 (43) | 204 (44) | 409 (43) |  |
All types of smoking combined | Â | Â | Â | Â | Â | Â | Â |
   Never |  | 156 | 156 (35) |  | 466 | 466 (49) | < .0001 |
   Former (> 2 yrs. Since quitting) | 159 (55) |  | 159 (36) | 319 (66) |  | 319 (34) |  |
   Current | 130 (45) |  | 130 (29) | 163 (34) |  | 163 (17) |  |
   Pack-yearsb, Mean ± SD | 45 ± 35 |  |  | 25 ± 27 |  |  | < .0001 |
Histology | Â | Â | Â | Â | Â | Â | Â |
   Adenocarcinoma | 80 (28) | 76 (49) | 156 (35) |  |  |  |  |
   Squamous cell carcinoma | 68 (24) | 9 (6) | 77 (17) |  |  |  |  |
   Small-cell carcinoma | 28 (10) | 4 (3) | 32 (7) |  |  |  |  |
   Large cell carcinoma | 21 (7) | 6 (4) | 27 (6) |  |  |  |  |
   Others/Mixed | 46 (16) | 26 (17) | 72 (16) |  |  |  |  |
Not classified/clinical diagnosis | 46 (16) | 35 (22) | 81 (18) | Â | Â | Â | Â |