Table 4 Associations between mitochondrial DNA integrity (ND4/ND1 divided by ND1/nuclear genome) and breast cancer risk

Overall

Quartile 1 (0.34–0.90)

129

152

Reference

Quartile 2 (0.90–1.00)

126

102

1.06

(0.68–1.66)

0.79

Quartile 3 (1.00–1.11)

133

142

1.56

(0.95–2.56)

0.08

Quartile 4 (1.11–2.59)

130

142

1.20

(0.69–2.08)

0.52

Continuous variable

519

539

1.07

(0.75–1.52)

0.73

ER+

Quartile 1 (0.34–0.90)

129

20

Reference

–

–

Quartile 2 (0.90–1.00)

126

50

1.61

(0.78–3.35)

0.20

Quartile 3 (1.00–1.11)

133

79

2.59

(1.19–5.66)

0.02

Quartile 4 (1.11–2.59)

130

89

2.47

(1.05–5.80)

0.04

Continuous variable

519

238

1.54

(0.87–2.72)

0.14

ER−

Quartile 1 (0.34–0.90)

129

128

Reference

–

–

Quartile 2 (0.90–1.00)

126

40

0.98

(0.55–1.74)

0.94

Quartile 3 (1.00–1.11)

133

47

1.22

(0.62–2.39)

0.56

Quartile 4 (1.11–2.59)

130

41

0.96

(0.46–2.00)

0.92

Continuous variable

519

256

0.99

(0.63–1.54)

0.95