Table 2.
Characteristics of case and control subjects in the included studies
| Study | No. of subjects | Median age, y (range) | Female | Never smoker | Never drinker | High school education or beyond | Urban residence |
| No. (%) | No. (%) | No. (%) | No. (%) | No. (%) | |||
| South Africa | Control subjects: 1110 | 59 (26–88) | 462 (42) | 616 (55) | 506 (46) | 593 (53) | 975 (88) |
| Case subjects: 697 | 58 (29–90) | 268 (38) | 222 (32) | 234 (34) | 264 (38) | 538 (77) | |
| Australia | Control subjects: 424 | 64 (34–80) | 182 (43) | 209 (49) | 57 (13) | 424 (100) | 271 (64) |
| Case subjects: 211 | 64 (34–79) | 90 (43) | 52 (25) | 29 (14) | 211 (100) | 131 (62) | |
| Central and Eastern Europe | Control subjects: 314 | 59 (39–76) | 36 (11) | 107 (34) | 40 (13) | 300 (96) | 221 (70) |
| Case subjects: 157 | 58 (39–80) | 18 (11) | 19 (12) | 7 (4) | 149 (95) | 80 (51) | |
| Brazil | Control subjects: 314 | 58 (33–89) | 68 (22) | 95 (30) | 127 (40) | 28 (9) | 256 (82) |
| Case subjects: 157 | 60 (33–91) | 34 (22) | 24 (15) | 30 (19) | 7 (4) | 96 (61) | |
| Iran | Control subjects: 221 | 65 (31–85) | 115 (52) | 175 (79) | 214 (97) | 15 (7) | 55 (25) |
| Case subjects: 220 | 64 (30–88) | 114 (52) | 164 (75) | 216 (98) | 5 (2) | 55 (25) | |
| China | Control subjects: 119 | 57 (34–73) | 46 (39) | 53 (45) | 68 (57) | 57 (48) | 71 (60) |
| Case subjects: 119 | 58 (36–70) | 46 (39) | 53 (45) | 71 (60) | 75 (63) | 63 (53) | |
| All studies | Control subjects: 2502 | 60 (26–89) | 909 (36) | 1255 (50) | 1012 (40) | 1417 (57) | 1849 (74) |
| Case subjects: 1561 | 60 (29–91) | 570 (37) | 534 (34) | 587 (38) | 711 (46) | 963 (62) |