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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.