Table 4.

HR of breast cancer associated with physical activity in the JACC study

Physical activity
CasesPerson-yearsAge adjusted
Multivariate*
Time spent walking (h/d)Time spent exercising (h/wk)HR (95% CI)HR (95% CI)
<1<193130,2791.00 (Reference)1.00 (Reference)
≥1<168125,5501.18 (0.79 – 1.77)1.13 (0.75 – 1.69)
<1≥13237,8850.76 (0.56 – 1.04)0.82 (0.60 – 1.12)
≥1≥11446,3420.42 (0.24 – 0.74)0.45 (0.25 – 0.78)
P for interaction0.0350.041
  • * Adjusted for age, BMI, alcohol drinking, age at menarche, education level, parity, age at birth of first child, use of exogenous female hormone, family history of breast cancer in a first-degree relative, menopausal status, and menopausal age for postmenopausal women.