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Table 1 Family histories* of all women under study (N = 1,987), of all women with breast cancer (n = 136) and of all women with breast cancer under the age of 50 (n = 73)

From: A family history of breast cancer will not predict female early onset breast cancer in a population-based setting

Presence of Family characteristics All women Women with breast cancer
   Breast cancer
at any age
Log rank; P Breast cancer
under age 50
Log rank; P
  N (%) N (%)   N (%)  
Total 1987 (100) 136 (6.8)   73 (3.7)  
≥ 2 cases of female breast cancer in first or second-degree relatives 614 (30.9) 54 (39.7) 7.39; P = .007 31 (5.0) 5.02; P = .03
≥ 2 cases of female breast cancer in first-degree relatives 165 (8.3) 20 (14.7) 5.23; P = .02 13 (17.8) 9.85; P = .002
≥ 1 case of female breast cancer under age 50 789 (39.7) 52 (6.6) 12.47; P = .0004 35 (4.4) 7.85; P = .005
≥ 2 cases of female breast cancer under age 50 113 (5.7) 10 (8.8) 1.92; P = .17 10 (8.8) 12.33; P = .0004
≥ 1 case of female breast cancer under age 40 231 (11.6) 18 (7.8) 12.01; P = .0005 12 (5.2) 8.52; P = .004
≥ 2 cases of female breast cancer under age 40 10 (0.5) - - - -
≥ 1 case of female breast cancer under age 30 33 (1.7) 1 (3.0) - 1 (3.0) -
Male breast cancer 12 (0.6) 1 (8.0) - 1 (8.0) -
Bilateral breast cancer in affected sister (index patient) 104 (5.2) 16 (15.4) 13.94; P = .0002 11 (10.6%) 15.00; P = .0001
Ovarian cancer 54 (2.7) 5 (9.3) 1.93; P = .16 3 (5.5%) 1.23; P = .27
Breast and ovarian cancer in one person 8 (0.4) 2 (25.0) 12.05; P = .0005 2 (25%) 14.00; P = .0002
Prostate cancer under age 60 43 (2.1) 1 (2.3)   1 (2.3%)  
DCIS in affected sister (index patient) 169 (8.5) 15 (8.9) 0.97; P = .32 7 (4.1%) 0.04; P = .84
  1. * To avoid dependency between women in families with more than one sister, sisters other than the index patient were excluded from the family history of the women under study.