Table 2 Hazard ratio (HR) and 95% confidence interval (CI) for oral contraceptive use, reproductive variables and colorectal cancer among women in the European Prospective Investigation into Cancer and Nutrition cohort

From: Oral contraceptives, reproductive history and risk of colorectal cancer in the European Prospective Investigation into Cancer and Nutrition

Variable

Number of cases/non-cases a

Age and center-stratified, HR (95% CI)

Multivariable adjusted, HR (95% CI) b

Oral contraceptive use

 Never

1040/138 359

1.00 (reference)

1.00 (reference)

 Ever

822/196 040

0.93 (0.84–1.03)

0.92 (0.83–1.02)

Oral contraceptive use (among post-menopausal women)

 Never

908/89 064

1.00 (reference)

1.00 (reference)

 Ever

469/67 757

0.85 (0.75–0.96)

0.84 (0.74–0.95)

Oral contraceptive use (among pre-/peri-menopausal women)

 Never

132/49 295

1.00 (reference)

1.00 (reference)

 Ever

353/128 283

1.22 (0.99–1.51)

1.19 (0.96–1.48)

 P-interaction

 

<0.01

<0.01

Duration of oral contraceptive use (years) c

 ⩽1

161/36 175

1.00 (reference)

1.00 (reference)

 2–4

167/42 208

0.99 (0.80–1.24)

0.99 (0.80–1.23)

 5–9

150/42 409

0.94 (0.75–1.18)

0.93 (0.74–1.17)

 ⩾10

264/58 041

1.10 (0.90–1.36)

1.09 (0.89–1.35)

 P-trend

 

0.37

0.41

Age at menarche

 <12

258/49 935

1.00 (reference)

1.00 (reference)

 12

358/70 982

0.95 (0.81–1.11)

0.95 (0.81–1.12)

 13

457/85 998

0.96 (0.83–1.12)

0.97 (0.84–1.14)

 14

424/71 912

0.95 (0.82–1.12)

0.97 (0.83–1.14)

 ⩾15

352/52 954

0.95 (0.80–1.12)

0.96 (0.82–1.14)

 P-trend

 

0.64

0.80

Age at menopause d

 ⩽50

654/77 482

1.00 (reference)

1.00 (reference)

 51–52

200/20 489

1.06 (0.90–1.25)

1.07 (0.91–1.25)

 53–55

196/18 391

1.06 (0.90–1.25)

1.07 (0.91–1.26)

 >55

59/5084

0.99 (0.76–1.30)

1.00 (0.76–1.31)

 P-trend

 

0.58

0.54

Type of menopause d

 Natural

1303/147 920

1.00 (reference)

1.00 (reference)

 Surgical

88/9 875

1.14 (0.91–1.42)

1.13 (0.91–1.41)

Induced or spontaneous abortion

 Never

1129/180 995

1.00 (reference)

1.00 (reference)

 Ever

221/45 509

1.01 (0.87–1.18)

1.00 (0.86–1.17)

Full-term pregnancy

 Never

231/49 342

1.00 (reference)

1.00 (reference)

 Ever

1568/267 467

0.96 (0.83–1.10)

0.96 (0.83–1.10)

Number of full-term pregnancies e

 1

250/49 177

1.00 (reference)

1.00 (reference)

 2

721/129 409

1.16 (1.00–1.34))

1.16 (1.01–1.35)

 3

384/61 490

1.15 (0.98–1.36)

1.16 (0.98–1.36)

 ⩾4

213/27 391

1.17 (0.97–1.41)

1.17 (0.97–1.42)

 P-trend

 

0.15

0.15

Age at first full-term pregnancy e

 ⩽20

210/40 007

1.00 (reference)

1.00 (reference)

 21–23

433/71 912

1.01 (0.86–1.19)

1.02 (0.86–1.21)

 24–25

320/52 140

0.97 (0.81–1.16)

0.98 (0.82–1.18)

 26–30

439/75 488

0.90 (0.76–1.07)

0.92 (0.77–1.09)

 >30

163/26 886

0.98 (0.79–1.20)

0.99 (0.80–1.22)

 P-trend

 

0.22

0.30

Breastfeeding e

 Never

211/39 471

1.00 (reference)

1.00 (reference)

 Ever

1273/218 695

1.12 (0.97–1.31)

1.13 (0.97–1.32)

  1. a The number of cases and non-cases do not add up to the total number of 1878 cases and 335 924 non-cases because of missing values.
  2. b From a Cox proportional hazards model stratified by the European Prospective Investigation into Cancer and Nutrition participating center and age at recruitment, and adjusted for smoking status (never, former, current), diabetes mellitus (never, ever), body mass index (<25, ⩾25–<30, ⩾30 kg m−2), physical activity (inactive, moderately inactive, moderately active, active), and alcohol use (<0.58, ⩾0.58–<3.61, ⩾3.61–<11.08, ⩾11.08 g per day).
  3. c Among ever oral contraceptive users only.
  4. d Among post-menopausal women only.
  5. e Among women with a full-term pregnancy.
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