Table 1.
Characteristics of 2,437 thyroid cancer casesa included in the study population
| Denmark | Finland | Norway | Swedenb | Total | |
|---|---|---|---|---|---|
| Total thyroid cancer cases (n) | 400 | 140 | 986 | 911 | 2,437 |
| Histologic typea | |||||
| Papillary carcinoma | 306 (77%) | 114 (81%) | 817 (83%) | 730 (82%) | 1,967 (81%) |
| Follicular carcinoma | 65 (16%) | 19 (14%) | 111 (11%) | 86 (10%) | 281 (12%) |
| Medullary carcinoma | 24 (6%) | 6 (4%) | 46 (5%) | 61 (7%) | 137 (6%) |
| Anaplastic carcinoma | <5c | <5c | <5c | <5c | 6 (<1%) |
| Other histology | 5 (1%) | <5c | 9 (<1%) | 13 (1%) | 28 (1%) |
| Sex | |||||
| Female | 301 (75%) | 110 (79%) | 760 (77%) | 709 (78%) | 1,880 (77%) |
| Male | 99 (25%) | 30 (21%) | 226 (23%) | 202 (22%) | 557 (23%) |
| Year of birth | |||||
| 1967-1969 | N/A | N/A | 243 (25%) | N/A | 243 (10%) |
| 1970-1979 | 222 (56%) | N/A | 502 (51%) | 451 (50%) | 1,175 (48%) |
| 1980-1989 | 144 (36%) | 56 (40%) | 184 (19%) | 352 (39%) | 736 (30%) |
| 1990-1999 | 32 (8%) | 79 (56%) | 52 (5%) | 94 (10%) | 257 (11%) |
| 2000-2013 | <5b | 5 (4%) | 5 (<1%) | 14 (2%) | 26 (1%) |
| Age at diagnosis (years) | |||||
| 0-9 | 8 (2%) | 9 (6%) | 7 (<1%) | 24 (3%) | 48 (2%) |
| 10-19 | 73 (18%) | 61 (44%) | 110 (11%) | 185 (20%) | 429 (18%) |
| 20-29 | 163 (41%) | 70 (50%) | 299 (30%) | 375 (41%) | 907 (37%) |
| 30-39 | 155 (39%) | <5c | 393 (40%) | 312 (34%) | 860 (35%) |
| 40-48 | <5c | <5c | 177 (18%) | 15 (2%) | 193 (8%) |
| Mean age (years) at diagnosis (SD) | 26·2 (7·8) | 18·9 (4·8) | 30·9 (8·7) | 25·7 (7·9) | 27·5 (8·7) |
| Year of cancer diagnosis | |||||
| 1985-1989 | 6 (2%) | 0 (0%) | 32 (3%) | 10 (1%) | 48 (2%) |
| 1990-1999 | 45 (11%) | 2 (1%) | 133 (13%) | 111 (12%) | 291 (12%) |
| 2000-2009 | 166 (42%) | 39 (28%) | 346 (35%) | 369 (41%) | 920 (38%) |
| 2010-2015 | 183 (46%) | 99 (71%) | 475 (48%) | 421 (46%) | 1,178 (48%) |
N/A = not applicable
a
The relatively high number of cases in Norway and Sweden was mainly a function of the year of establishment of the birth registry (with Norway having the oldest, allowing for more time between birth and thyroid cancer diagnosis) and the size of the underlying population (with Sweden having the largest).
b
18 unspecified cases from Sweden were excluded
c
Numbers suppressed due to <5 cases and/or controls