Table 4.

Vigorous exercise at baseline in relation to incidence of breast cancer by age, BMI, parity, family history of breast cancer, menopausal status, and age

h/wkCasesIRRa (95% CI)CasesIRR (95% CI)Pinteraction
Age < 50Age ≥ 50
<12871.00 (Ref.)4861.00 (Ref.)
1550.77 (0.58–1.03)620.90 (0.69–1.18)
2630.84 (0.64–1.11)861.12 (0.88–1.41)
3–4750.83 (0.64–1.08)841.02 (0.80–1.29)
5–6310.74 (0.51–1.08)381.02 (0.73–1.43)
≥7260.57 (0.38–0.86)370.91 (0.65–1.27)
Ptrend = 0.003Ptrend = 0.980.44
BMI < 30BMI ≥ 30
<14181.00 (Ref.)3501.00 (Ref.)
1710.86 (0.67–1.11)450.83 (0.61–1.13)
21011.09 (0.88–1.36)480.85 (0.62–1.15)
3–41100.98 (0.79–1.21)490.88 (0.65–1.19)
5–6500.96 (0.71–1.30)180.74 (0.46–1.19)
≥7410.73 (0.53–1.01)220.81 (0.52–1.25)
Ptrend = 0.24Ptrend = 0.080.28
NulliparousParous
<11371.00 (Ref.)6361.00 (Ref.)
1190.69 (0.40–1.04)980.90 (0.73–1.12)
2290.82 (0.54–1.23)1201.05 (0.86–1.28)
3–4481.12 (0.80–1.59)1110.87 (0.71–1.07)
5–6160.79 (0.46–1.34)530.92 (0.69–1.23)
≥7180.70 (0.48–1.31)450.72 (0.53–0.97)
Ptrend = 0.55Ptrend = 0.050.26
Family history: yesFamily history: no
<11231.00 (Ref.)6501.00 (Ref.)
1160.73 (0.43–1.24)1010.87 (0.70–1.07)
2231.04 (0.66–1.64)1260.99 (0.82–1.20)
3–4281.05 (0.68–1.60)1310.91 (0.75–1.11)
5–6110.88 (0.47–1.65)580.89 (0.68–1.17)
≥7100.75 (0.39–1.44)530.74 (0.56–0.99)
Ptrend = 0.59Ptrend = 0.050.97
PremenopausalPostmenopausal
<12381.00 (Ref.)4251.00 (Ref.)
1520.88 (0.65–1.19)470.81 (0.60–1.09)
2630.99 (0.75–1.31)651.01 (0.78–1.31)
3–4740.99 (0.76–1.29)650.94 (0.72–1.22)
5–6320.89 (0.61–1.30)270.85 (0.60–1.33)
≥7240.64 (0.42–0.98)320.94 (0.66–1.36)
Ptrend = 0.13Ptrend = 0.550.76
  • aIRRs adjusted for age (single year), questionnaire cycle, years of education (≤12, 13–14, 16, ≥17), parity (0, 1, 2, ≥3), vegetable/fruit dietary pattern (quintiles), and meat/fried foods dietary pattern (quintiles).