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Table 2 Characteristics of controls in the nested case–control study according to benign breast disease category

From: Benign breast disease, recent alcohol consumption, and risk of breast cancer: a nested case–control study

 

Category of benign breast disease

Descriptive characteristic

Nonproliferative

Proliferative without atypia

Atypical hyperplasia

Mean

   

   Age at biopsy (y)

42.5

43.7

50.1

   Year of biopsyb

1979

1980

1983

   Age at menarche (y)

12.7

12.5

12.9

   Age at first birthc (y)

24.8

24.9

25.0

   Age at menopaused

46.6

46.5

47.2

   Body mass index, kg/m2

25.1

24.6

24.5

   Parity

2.8

2.7

2.9

   Recent alcohol consumption, g/day

4.8

5.4

6.6

Frequency, %

   

   Premenopausal at biopsy

76.5

76.1

57.1

   Family history of breast cancer

11.2

13.3

18.3

   Nulliparous

6.5

8.2

5.6

   Natural menopause d

46.8

50.7

48.5

   Bilateral oophorectomyd

20.1

16.8

17.5

  1. aNurses' Health Study I (1976 to 1994) and II (1989 to 1995). bMedian. cAmong parous women only. dAmong postmenopausal women.