Table 3 Relative risk of breast cancer in relation to participant’s age at death of parent, Breakthrough Generations Study

All mothers

Mother deceased

No

916

1.00

700

1.00

146

1.00

Yes

867

0.99 (0.89-1.10)

690

1.00 (0.89-1.13)

121

0.96 (0.72-1.27)

  Age of participant at mother’s death, years

  <20

75

1.31 (1.02-1.67)

55

1.21 (0.89-1.61)

13

1.67 (0.93-2.98)

  20-29

91

1.02 (0.82-1.27)

72

1.04 (0.81-1.33)

13

1.01 (0.57-1.80)

  30-39

178

1.07 (0.91-1.27)

135

1.04 (0.86-1.26)

26

1.09 (0.71-1.68)

  40-49

221

0.88 (0.75-1.03)

187

0.95 (0.80-1.13)

23

0.62 (0.39-0.99)

  ≥50

302

0.94 (0.81-1.10)

241

0.96 (0.81-1.14)

46

1.01 (0.68-1.49)

P trend=0.059

P trend=0.22

P trend=0.46

Mothers who did not have breast or ovarian cancer

Mother deceased

No

790

1.00

603

1.00

128

1.00

Yes

633

0.94 (0.83-1.07)

507

0.98 (0.85-1.13)

88

0.82 (0.60-1.13)

  Age of participant at mother’s death, years

  <20

41

1.17 (0.85-1.61)

29

1.05 (0.72-1.55)

7

1.35 (0.62-2.92)

  20-29

54

1.04 (0.78-1.38)

43

1.07 (0.78-1.47)

7

0.86 (0.40-1.86)

  30-39

119

1.05 (0.86-1.29)

92

1.05 (0.84-1.32)

16

0.92 (0.54-1.57)

  40-49

173

0.86 (0.72-1.03)

150

0.98 (0.80-1.19)

16

0.50 (0.28-0.87)

  ≥50

246

0.89 (0.75-1.05)

193

0.90 (0.75-1.09)

42

0.98 (0.65-1.49)

P trend=0.046

P trend=0.19

P trend=0.86

All fathers

Father deceased

No

730

1.00

568

1.00

104

1.00

Yes

1053

0.95 (0.85-1.06)

822

0.92 (0.81-1.04)

163

1.23 (0.92-1.65)

  Age of participant at father’s death, years

  <20

105

0.94 (0.76-1.16)

80

0.88 (0.69-1.12)

18

1.37 (0.82-2.30)

  20-29

163

0.96 (0.81-1.15)

133

0.98 (0.80-1.19)

22

1.12 (0.69-1.80)

  30-39

259

0.92 (0.79-1.06)

205

0.90 (0.76-1.07)

37

1.08 (0.72-1.61)

  40-49

326

1.00 (0.87-1.16)

257

0.98 (0.83-1.15)

49

1.30 (0.89-1.90)

  ≥50

200

0.91 (0.77-1.09)

147

0.82 (0.67-1.00)

37

1.50 (0.97-2.31)

P trend=0.97

P trend=0.56

P trend=0.40