Table 1:

Participant characteristics

CharacteristicIntracranial tumourLeukemiaNon-Hodgkin lymphomaHodgkin lymphoma
No (%) of patients*
n = 2245
No. (%) of controls*
n = 22 450
No (%) of patients*
n = 3667
No. (%) of controls*
n = 36 667
No (%) of patients*
n = 1331
No. (%) of controls*
n = 13 300
No (%) of patients*
n = 564
No. (%) of controls*
n = 5640
Sex
 Male1341 (59.7)13 410 (59.7)2130 (58.1)21 300 (58.1)836 (62.8)8350 (62.8)316 (56.0)3160 (56.0)
 Female904 (40.3)9040 (40.3)1537 (41.9)15 367 (41.9)495 (37.2)4950 (37.2)248 (44.0)2480 (44.0)
Age, yr, median (IQR)
 At entry5.3 (11.6)5.4 (11.5)3.8 (11.0)3.9 (11.0)9.7 (11.5)9.5 (11.5)11.1 (8.6)11.0 (8.6)
 At first CT scan9.0 (9.6)7.8 (9.9)6.3 (8.4)8.5 (10.4)9.5 (10.8)12.4 (8.9)14.8 (6.0)11.1 (7.2)
Degree of urbanization
 Metropolitan1299 (57.9)13 293 (59.2)2164 (59.0)21 966 (59.9)821 (61.7)8227 (61.9)376 (66.7)3436 (60.9)
 City726 (32.3)7203 (32.1)1159 (31.6)11 379 (31)385 (28.9)3989 (30.0)147 (26.1)1716 (30.4)
 Town105 (4.7)1031 (4.6)185 (5.0)1734 (4.7)64 (4.8)562 (4.2)25 (4.4)252 (4.5)
 Rural area65 (2.9)681 (3.0)112 (3.1)1180 (3.2)40 (3.0)351 (2.6)12 (2.1)160 (2.8)
 Missing50 (2.2)242 (1.1)47 (1.3)408 (1.1)21 (1.6)171 (1.3)4 (0.7)76 (1.3)
Annual family income, percentile
 > 75th519 (23.1)5693 (25.4)969 (26.4)9591 (26.2)312 (23.4)3039 (22.8)134 (23.8)1182 (21)
 50th to 75th507 (22.6)5610 (25.0)837 (22.8)9079 (24.8)332 (24.9)3451 (25.9)137 (24.3)1487 (26.4)
 25th to 49th558 (24.9)5634 (25.1)880 (24)9111 (24.8)320 (24.0)3354 (25.2)137 (24.3)1444 (25.6)
 < 25th657 (29.3)5491 (24.5)970 (26.5)8847 (24.1)364 (27.3)3442 (25.9)156 (27.7)1517 (26.9)
 Missing4 (0.2)22 (0.1)11 (0.3)39 (0.1)3 (0.2)14 (0.1)0 (0.0)10 (0.2)
Calendar year of cohort entry
 2000–20042017 (89.8)20 155 (89.8)3119 (85.1)31 306 (85.4)1267 (95.2)12 658 (95.2)557 (98.8)5570 (98.8)
 2005–2009195 (8.7)1954 (8.7)448 (12.2)4401 (12)52 (3.9)527 (4.0)6 (1.1)60 (1.1)
 2010 or later33 (1.5)341 (1.5)100 (2.7)960 (2.6)12 (0.9)115 (0.9)< 310 (0.2)
Number of CT scans
 02207 (98.3)22 162 (98.7)3631 (99.0)36 219 (98.8)1311 (98.5)13 119 (98.6)557 (98.8)5524 (97.9)
 1–332 (1.4)282 (1.3)30 (0.8)435 (1.2)16 (1.2)175 (1.3)6 (1.1)113 (2.0)
 ≥ 46 (0.3)6 (0.0)6 (0.2)13 (0.0)4 (0.3)6 (0.0)< 33 (0.1)
Exposure to other high radiation procedures
 Cystography< 3 (0.0)61 (0.3)10 (0.3)110 (0.3)3 (0.2)27 (0.2)< 3 (0.2)10 (0.2)
 Cardiac catheterization< 3 (0.0)18 (0.1)5 (0.1)27 (0.1)< 3 (0.1)8 (0.1)< 3 (0.2)7 (0.1)
 Renal scan0 (0.0)20 (0.1)< 3 (0.1)22 (0.1)< 3 (0.1)6 (0.0)0 (0.0)6 (0.1)
 Renography0 (0.0)11 (0.0)< 3 (0.1)14 (0.0)< 3 (0.2)4 (0.0)0 (0.0)5 (0.1)
 Other5 (0.2)23 (0.1)< 3 (0.1)35 (0.1)< 3 (0.1)17 (0.1)0 (0.0)4 (0.1)
  • Note: CT = computed tomography, IQR = interquartile range.

  • * Unless indicated otherwise. National Health Insurance Research Database policy on protecting confidentiality requires suppression of cells < 3.

  • Degree of urbanization of townships in Taiwan was stratified into 7 levels according to official statistics. (46) In this study, we classified the townships into 4 categories, namely metropolitan (level 1 and 2), city (level 3 and 4), town (level 5 and 6) and rural area (level 7).

  • Includes positron emission tomography, skeletal scintigraphy, lung perfusion scan, hepatobiliary scintigraphy, Meckel scan and gastric emptying tests.