Table 1

Characteristics of cases and controls, overall and by tumour location

CharacteristicsColonRectumOverall
CasesControlsCasesControlsCasesControls
N19 72692 999925444 07828 9801 37 077
Duration of follow-up* (years), median (IQR)8.2 (5.0–12.4)8.2 (5.0–12.3)8.0 (4.8–12.0)8.0 (4.8–12.0)8.1 (5.0–12.3)8.1 (4.9,12.2)
Age (years), median (IQR)73 (64–79)72 (64–79)71 (62–78)70 (62–78)72 (64,79)72 (63,79)
Sex
 Male10 465 (53.1)48 960 (52.6)5630 (60.8)26 688 (60.5)16 095 (55.5)75 648 (55.2)
 Female9261 (46.9)44 039 (47.4)3624 (39.2)17 390 (39.5)12 885 (44.5)61 429 (44.8)
BMI category†
 Normal5561 (28.2)28 384 (30.5)2664 (28.8)13 132 (29.8)8225 (28.4)41 516 (30.3)
 Overweight7016 (35.6)31 397 (33.8)3185 (34.4)14 877 (33.8)10 201 (35.2)46 274 (33.8)
 Obese3807 (19.3)15 374 (16.5)1586 (17.1)7088 (16.1)5393 (18.6)22 462 (16.4)
 Missing3342 (16.9)17 844 (19.2)1819 (19.7)8981 (20.4)5161 (17.8)26 825 (19.6)
Smoking status‡
 Never smoker8268 (41.9)39 724 (42.7)3599 (38.9)18 327 (41.6)11 867 (40.9)58 051 (42.3)
 Current smoker (trivial-light)718 (3.6)3391 (3.6)367 (4.0)1664 (3.8)1085 (3.7)5055 (3.7)
 Current smoker (moderate)996 (5.0)5081 (5.5)565 (6.1)2485 (5.6)1561 (5.4)7566 (5.5)
 Current smoker (heavy)1051 (5.3)4887 (5.3)532 (5.7)2522 (5.7)1583 (5.5)7409 (5.4)
 Current smoker (amount unknown)1217 (6.2)5539 (6.0)547 (5.9)2569 (5.8)1764 (6.1)8108 (5.9)
 Ex-smoker5769 (29.2)24 636 (26.5)2691 (29.1)11 403 (25.9)8460 (29.2)36 039 (26.3)
 Missing1707 (8.7)9741 (10.5)953 (10.3)5108 (11.6)2660 (9.2)14 849 (10.8)
Alcohol use§
 Non-drinker1734 (8.8)9244 (9.9)758 (8.2)4047 (9.2)2492 (8.6)13 291 (9.7)
 Current drinker (trivial-light)5757 (29.2)26 460 (28.5)2623 (28.3)12 643 (28.7)8380 (28.9)39 103 (28.5)
 Current drinker (moderate)2134 (10.8)8835 (9.5)1250 (13.5)4674 (10.6)3384 (11.7)13 509 (9.9)
 Current drinker (heavy)385 (2.0)1297 (1.4)211 (2.3)743 (1.7)596 (2.1)2040 (1.5)
 Current drinker (amount unknown)5970 (30.3)27 920 (30.0)2467 (26.7)12 485 (28.3)8437 (29.1)40 405 (29.5)
 Ex-drinker350 (1.8)1550 (1.7)165 (1.8)701 (1.6)515 (1.8)2251 (1.6)
 Missing3396 (17.2)17 693 (19.0)1780 (19.2)8785 (19.9)5176 (17.9)26 478 (19.3)
Diabetes history1796 (9.1)7280 (7.8)761 (8.2)3298 (7.5)2557 (8.8)10 578 (7.7)
Chronic NSAID use¶1450 (7.4)8443 (9.1)645 (7.0)3831 (8.7)2095 (7.2)12 274 (9.0)
Chronic aspirin use¶3934 (19.9)18 287 (19.7)1635 (17.7)7886 (17.9)5569 (19.2)26 173 (19.1)
Use of colonoscopy773 (3.9)2828 (3.0)242 (2.6)1209 (2.7)1015 (3.5)4037 (2.9)
  • Data are n (%) unless otherwise stated.

  • *Date from registration to date of colorectal cancer diagnosis.

  • †Normal: 18.5–24.9, overweight: 25.0–29.9, obese: ≥30.0.

  • ‡Trivial, light, moderate or heavy current smoking were assigned when either the general practitioner had recorded a Read code with one of these terms, or when the units per day were recorded as 0-1 (trivial), 1–9 (light), 10–19 (moderate), ≥20 (heavy).

  • § Trivial, light, moderate, or heavy current drinking were assigned when either the general practitioner had recorded a Read code with one of these terms, or when the units per day were recorded as 0–1 (trivial), 1–2 (light), 3–6 (moderate), ≥ 7 (heavy).

  • ¶Cumulative days prescribed for ≥ 365 days.

  • BMI, body mass index; NSAID, non-steroidal anti-inflammatory drug.