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Table 2 Relative risks of breast cancer by body fatness at ages 5, 10, and 20 years, and during childhood and adolescence among 109,267 premenopausal Nurses' Health Study II participants (1989–2001)

From: Body fatness during childhood and adolescence and incidence of breast cancer in premenopausal women: a prospective cohort study

 

Casesa (n = 1318)

Person-years

Age-adjusted RR (95% CI)

Multivariate RR (95% CI)b

Figure at age 5 years

   1

350

252,779

1.00 (ref.)

1.00 (ref.)

   2

431

335,974

0.97 (0.84–1.11)

0.96 (0.83–1.11)

   3

304

251,625

0.89 (0.76–1.04)

0.88 (0.76–1.03)

   4

173

133,574

0.94 (0.78–1.13)

0.93 (0.77–1.12)

   ≥ 5

60

70,740

0.59 (0.45–0.78)

0.57 (0.43–0.75)

P for trendc

  

0.002

0.001

Figure at age 10 years

   1

277

191,720

1.00 (ref.)

1.00 (ref.)

   2

423

323,197

0.95 (0.82–1.11)

0.96 (0.82–1.11)

   3

307

239,185

0.92 (0.79–1.09)

0.93 (0.79–1.10)

   4

197

165,957

0.84 (0.70–1.01)

0.84 (0.70–1.01)

   ≥ 5

114

124,633

0.62 (0.50–0.77)

0.61 (0.49–0.76)

P for trendc

  

<0.0001

<0.0001

Figure at age 20 years

   1

73

44,399

1.00 (ref.)

1.00 (ref.)

   2

414

271,292

1.04 (0.81–1.33)

1.05 (0.82–1.35)

   3

474

397,651

0.85 (0.67–1.09)

0.87 (0.68–1.11)

   4

247

219,136

0.81 (0.62–1.05)

0.81 (0.63–1.06)

   ≥ 5

110

112,213

0.71 (0.53–0.95)

0.70 (0.52–0.94)

P for trendc

  

<0.0001

<0.0001

Average childhood figure (ages 5–10 years)

   1

262

177,512

1.00 (ref.)

1.00 (ref.)

   1.5–2

416

322,714

0.92 (0.79–1.08)

0.93 (0.79–1.08)

   2.5–3

339

265,111

0.90 (0.77–1.06)

0.90 (0.76–1.06)

   3.5–4.5

253

215,175

0.82 (0.69–0.97)

0.81 (0.68–0.96)

   ≥ 5

48

64,180

0.49 (0.36–0.67)

0.48 (0.35–0.65)

P for trendc

  

<0.0001

<0.0001

Average adolescent figure (ages 10–20 years)

   1

56

34,780

1.00 (ref.)

1.00 (ref.)

   1.5–2

398

267,086

1.07 (0.81–1.41)

1.08 (0.82–1.43)

   2.5–3

449

366,516

0.92 (0.69–1.21)

0.93 (0.71–1.24)

   3.5–4.5

363

312,070

0.85 (0.64–1.13)

0.86 (0.65–1.14)

   ≥ 5

52

64,240

0.58 (0.40–0.85)

0.57 (0.39–0.83)

P for trendc

  

<0.0001

<0.0001

  1. aIncluding both invasive and in situ cases. bAdjusted for age (months), time period (6 periods), birthweight (<5.5, 5.5–6.9, 7–8.4, 8.5–9.9, ≥ 10 lb), height (inches), recent alcohol consumption (0, 0.1–1.4, 1.5–4.9, 5.0–9.9, ≥ 10 g/day), parity and age at first birth (nulliparous, 1–2 pregnancies with age at first birth <25 years, 1–2 pregnancies with age at first birth 25–29 years, 1–2 pregnancies with age at first birth ≥ 30 years, ≥ 3 pregnancies with age at first birth <25 years, ≥ 3 pregnancies with age at first birth 25–29 years, ≥ 3 pregnancies with age at first birth ≥ 30 years), oral contraceptive use (never, past use <4 years, past use ≥ 4 years, current use <4 years, current use ≥ 4 years), history of benign breast disease (yes, no), and first-degree family history of breast cancer (yes, no). cWald test of coefficient for body fatness modeled as an ordinal variable. CI, confidence interval; RR, relative risk.
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Breast Cancer Research

ISSN: 1465-542X

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