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Table 2 Number of breast cancers, person-years, rates, and RRs by demographic, reproductive, and anthropometric factors.

From: Breast cancer epidemiology according to recognized breast cancer risk factors in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial Cohort

 

Breast Cancers*

Woman-Years

Crude Rate

RR**

95% CI

Attained Age

     

   55–59

274

63,088

434.31

1.00

Ref.

   60–64

608

108,640

559.65

1.36

1.18–1.57

   65–69

582

104,433

557.30

1.44

1.24–1.67

   70–74

434

79,134

548.44

1.48

1.26–1.73

   75+

187

34,419

543.30

1.47

1.21–1.79

Race

     

   White

1,854

345,926

535.95

1.00

Ref.

   African-American

89

19,765

450.29

1.05

0.84–1.32

   Asian/Pacific Islander

111

17,230

644.23

1.14

0.86–1.51

   Other/unknown

31

6,793

456.35

0.92

0.64–1.32

Family history of breast cancer

     

   No

1696

336,410

504.15

1.00

Ref.

   Yes

389

53,304

729.78

1.44

1.29–1.60

Number of Live Births

     

   0

240

35,545

675.20

1.00

Ref.

   1

160

28,296

565.45

0.70

0.55–0.89

   2

524

88,510

592.02

0.76

0.62–0.92

   3

526

96,163

546.99

0.75

0.62–0.91

   4

331

66,673

496.45

0.72

0.59–0.88

   5+

301

73,888

407.37

0.65

0.53–0.80

Age at First Birth

     

   None

240

35,545

675.20

1.00

Ref.

   < 20

267

62,165

429.50

0.68

0.53–0.86

   20–24

901

181,709

495.85

0.74

0.59–0.91

   25–29

471

80,523

584.93

0.83

0.66–1.03

   30–34

148

20,822

710.79

1.03

0.81–1.31

   35+

47

6,894

681.75

1.02

0.74–1.41

Age at Menarche

     

   < 12 years

457

76,987

593.61

1.00

Ref.

   12–13 years

1099

209,082

525.63

0.86

0.77–0.97

   14–15 years

439

84,595

518.94

0.85

0.74–0.97

   ≥ 16 years

88

17,874

492.34

0.81

0.65–1.02

Age at Menopause

     

   < 45 years

123

25,254

487.05

1.00

Ref.

   45–49 years

340

64,113

530.31

1.07

0.87–1.31

   50–54 years

700

126,080

555.20

1.12

0.92–1.35

   55+ years

211

32,192

655.44

1.29

1.03–1.62

   Surgical menopause

574

122,386

469.01

0.84

0.69–1.02

   Radiation/medication

94

12,061

779.37

1.32

1.01–1.74

Menopausal hormone therapy use

     

   Never

571

134,329

425.08

1.00

Ref.

   Former

280

64,773

432.28

1.02

0.88–1.18

   Current, < 5 years

372

61,931

600.67

1.44

1.26–1.66

   Current, ≥ 5 years

847

125,006

677.57

1.67

1.49–1.87

Weight (kg)

     

   < 60

437

82,961

526.75

1.00

Ref.

   60 – 64.9

310

59,068

524.82

1.03

0.86–1.19

   65 – 69.9

311

56,091

554.46

1.18

0.97–1.30

   70 – 74.9

257

49,325

521.03

1.08

0.92–1.26

   75 – 79.9

267

47,072

567.22

1.21

1.03–1.42

   ≥ 80

486

91,892

528.88

1.20

1.04–1.38

Height (m)

     

   < 1.60

527

101,460

519.42

1.00

Ref.

   1.60 – 1.64

605

117,236

516.05

1.01

0.89–1.13

   1.65 – 1.69

561

102,205

548.90

1.06

0.94–1.20

   ≥ 1.70

385

66,707

577.15

1.11

0.97–1.27

BMI (kg/m2)

     

   < 18.5

25

5,135

486.85

0.88

0.59–1.32

   18.5 – 24.9

848

154,447

549.06

1.00

Ref.

   25 – 29

712

133,799

532.14

1.06

0.95–1.17

   30 – 34.9

305

59,109

516.00

1.10

0.97–1.26

   ≥ 35

173

32,478

532.67

1.21

1.02–1.43

  1. * Includes confirmed invasive cancers, confirmed in situ lesions, and self-reported cancers.
  2. ** Adjusted for attained age, screening center, age at menarche, age at menopause, family history of breast cancer, benign breast disease, height, and menopausal hormone therapy (all in categories as shown in the table), plus combined age at first birth and parity (nulliparous or first birth after 35 years, first birth before age 25, first birth 25–34 years, or unknown) and calendar time (5/31/1993 – 5/31/1995, 6/1/1995 – 5/31/1997, 6/1/1997 – 5/31/1999, 6/1/1999 – 5/31/2001, and 6/1/2001 – 5/31/2003). RRs for age at first birth and parity were adjusted for the other factor.
  3. Not shown are unknown parity (3 breast cancers and 638 person-years), age at first birth (11 breast cancers and 2,635 person-years), age at menarche (2 breast cancers and 1,177 person-years), age at or type of menopause (43 breast cancers and 7,628 person-years), menopausal hormone therapy use (15 breast cancers and 3,676 person-years), weight (17 breast cancers and 3,304 person-years), height (7 breast cancers and 2,107 person-years), and BMI (22 breast cancers and 4,747 person-years).
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BMC Cancer

ISSN: 1471-2407

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