Table 4 Risk factor associations with epithelial nuclear density among women with mostly fat (stromal area <10%) breast tissue (N = 99)

From: Stroma modifies relationships between risk factor exposure and age-related epithelial involution in benign breast

 

N

Mean (standard error)

Difference (standard error)a

p

Age

 <50 years

31

3720.5 (133.7)

  

 ≥50 years

68

3997.5 (159.3)

  

Race

 White (ref)

64

3974.8 (159.9)

Ref

 

 African American

30

3677.0 (167.5)

−311.1 (261.1)

0.2

 Other

5

4493.3 (370.3)

506.4 (544.9)

0.4

Body mass index (kg/m2)

 <25.0 (ref)

21

3892.3 (340.0)

Ref

 

 25.0 to 29.9

19

3940.6 (275.4)

55.8 (385.5)

0.9

 ≥30.0

59

3907.7 (131.6)

22.4 (298.5)

0.9

 Trend test β

  

−8.7 (16.7)

0.6

Mammographic density

 1—Fatty (ref)

19

3892.3 (207.6)

Ref

 

 2—Scattered fibroglandular

51

4153.1 (193.2)

263.4 (326.1)

0.4

 3—Heterogeneously dense

25

3510.4 (158.8)

−390.8 (377.6)

0.3

 4—Extremely dense

Xb

—

—

 

 Dense, NOS

Xb

—

—

 

 Missing

3

   

Age at menarche

 <13 years (ref)

57

3800.7 (164.1)

Ref

 

 ≥13 years

41

4077.1 (167.1)

284.0 (238.7)

0.2

 Missing

1

   

Parity

    

 Nulliparous (ref)

13

3929.8 (273.8)

Ref

 

 1–2 births

52

4006.2 (177.0)

72.1 (362.4)

0.8

 ≥3 births

34

3757.5 (183.4)

−188.3 (389.1)

0.6

Age at first term pregnancyc

 <26 years (ref)

57

3786.4 (132.5)

Ref

 

 ≥26 years

29

4146.8 (279.7)

358.4 (271.3)

0.2

Time since last birthc

 <10 years (ref)

7

3765.9 (320.3)

Ref

 

 10–19 years

20

3943.9 (251.6)

256.3 (553.0)

0.6

 ≥20 years

58

3902.8 (167.9)

273.5 (575.1)

0.6

 Missing

1

   

History of breastfeedingc

 Never (ref)

45

3906.7 (146.1)

Ref

 

 Ever

41

3909.2 (220.6)

−7.9 (259.3)

1.0

Breastfeeding durationc

 <3 months (ref)

58

3896.9 (124.6)

Ref

 

 ≥3 months

28

3930.7 (305.9)

26.3 (276.4)

0.9

Oral contraceptive duration

 Never (ref)

12

4068.4 (350.1)

Ref

 

 ≤10 years

69

3931.7 (144.7)

−154.4 (377.7)

0.7

 >10 years

17

3706.9 (260.0)

−384.8 (449.6)

0.4

 Missing

1

   

Oral contraceptive recency

 Never (ref)

12

4068.4 (350.1)

Ref

 

 ≤5 years ago

8

3609.8 (293.4)

−628.7 (608.6)

0.3

 >5 years ago

78

3915.7 (136.4)

−203.8 (371.6)

0.6

 Missing

1

   

Menopausal hormone therapy recencyd

 Never (ref)

34

3885.6 (253.6)

Ref

 

 ≤5 years ago

13

3618.7 (348.0)

−156.7 (430.0)

0.7

 >5 years ago

14

3981.4 (249.1)

41.6 (424.8)

0.9

  1. aAdjusted for age and surgery type (surgery type model adjusted only for age, age model adjusted only for surgery type)
  2. bCells with fewer than five patients were suppressed to maintain patient confidentiality
  3. cAmong parous women
  4. dAmong postmenopausal women
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