Characteristics of the study population
| All cholangiocarcinoma* | Intrahepatic cholangiocarcinoma* | Extrahepatic cholangiocarcinoma* | ||||
| Cases (n=8231) | Controls (n=37 389) | Cases (n=1458) | Controls (n=6773) | Cases (n=3972) | Controls (n=18221) | |
| n (%) | n (%) | n (%) | n (%) | n (%) | n (%) | |
| Gender | ||||||
| Female | 4317 (52.5) | 18 268 (48.9) | 674 (46.2) | 2937 (43.4) | 1783 (44.9) | 7523 (41.3) |
| Male | 3914 (47.5) | 19 121 (51.1) | 784 (53.8) | 3836 (56.6) | 2189 (55.1) | 10 698 (58.7) |
| Birth cohort | ||||||
| 1920–1929 | 4416 (53.7) | 19 266 (51.5) | 654 (44.9) | 2929 (43.3) | 2156 (54.3) | 9553 (52.4) |
| 1930–1939 | 2322 (28.2) | 10 939 (29.3) | 415 (28.5) | 1971 (29.1) | 1116 (28.1) | 5288 (29.0) |
| 1940–1949 | 1177 (14.3) | 5665 (15.1) | 296 (20.3) | 1426 (21.0) | 549 (13.8) | 2651 (14.6) |
| 1950–1960 | 316 (3.8) | 1519 (4.1) | 93 (6.4) | 447 (6.6) | 151 (3.8) | 729 (4.0) |
| Reference age† | ||||||
| ≤59 | 2736 (33.2) | 12 800 (34.2) | 538 (36.9) | 2542 (37.5) | 1412 (35.5) | 6604 (36.2) |
| 60–69 | 3003 (36.5) | 13 593 (36.4) | 502 (34.4) | 2320 (34.3) | 1416 (35.7) | 6507 (35.7) |
| ≥70 | 2492 (30.3) | 10 996 (29.4) | 418 (28.7) | 1911 (28.2) | 1144 (28.8) | 5110 (28.0) |
| Reference period‡ | ||||||
| 1961–1970 | 21 (0.3) | 94 (0.3) | 0 (0.0) | 0 (0.0) | 17 (0.4) | 77 (0.4) |
| 1971–1980 | 451 (5.5) | 1959 (5.2) | 46 (3.2) | 194 (2.9) | 256 (6.5) | 1141 (6.3) |
| 1981–1990 | 1796 (21.8) | 8012 (21.4) | 266 (18.2) | 1208 (17.8) | 979 (24.6) | 4408 (24.2) |
| 1991–2005 | 5963 (72.4) | 27 324 (73.1) | 1146 (78.6) | 5371 (79.3) | 2720 (68.5) | 12 595 (69.1) |
| Country | ||||||
| Finland | 3395 (41.2) | 15 306 (40.9) | 549 (37.7) | 2571 (38.0) | 1353 (34.1) | 6214 (34.1) |
| Iceland | 73 (0.9) | 305 (0.8) | 11 (0.7) | 48 (0.7) | 43 (1.1) | 186 (1.0) |
| Norway | 1349 (16.4) | 5870 (15.7) | 260 (17.8) | 1153 (17.0) | 610 (15.4) | 2699 (14.8) |
| Sweden | 3414 (41.5) | 15 908 (42.6) | 638 (43.8) | 3001 (44.3) | 1966 (49.5) | 9122 (50.1) |
| Ever worked in the printing industry | ||||||
| No | 8138 (98.9) | 36 979 (98.9) | 1426 (97.8) | 6703 (99.0) | 3933 (99.0) | 18 002 (98.8) |
| Yes | 93 (1.1) | 410 (1.1) | 32 (2.2) | 70 (1.0) | 39 (1.0) | 219 (1.2) |
| Occupational exposure to asbestos | ||||||
| No | 6861 (83.4) | 31 052 (83.0) | 1171 (80.3) | 5548 (81.9) | 3225 (81.2) | 14 727 (80.8) |
| Yes | 1370 (16.6) | 6337 (17.0) | 287 (19.7) | 1225 (18.1) | 747 (18.8) | 3494 (19.2) |
*2801 cases (1860 women and 941 men) were classified as cholangiocarcinoma but the coding scheme did not allow the distinction between intra- and extrahepatic cholangiocarcinoma. These cases are included in the ‘All cholangiocarcinoma’ column.
†Reference age defined as age at diagnosis for cases and age at sampling for controls.
‡Reference period defined as period of diagnosis for cases and period of sampling for controls.