Table 4.

Recreational physical activity and risk of invasive breast cancer by time of exercise and family history

Period of All women
No family history of breast cancer
Family history of breast cancer
Controls (n = 7,630)Invasive cases (n = 6,391)OR (95% CI)*Controls (n = 6,438)Invasive cases (n = 4,902)OR (95% CI)*Controls (n = 950)Invasive cases (n = 1,283)OR (95% CI)*
Lifetime
    0 h/wk9518221.00 (Reference)7996201.00 (Reference)1121551.00 (Reference)
    0.1-3 h/wk5,4034,4980.90 (0.81-1.00)4,5303,4350.91 (0.81-1.03)7139310.90 (0.69-1.19)
    3.1-6 h/wk8157390.97 (0.84-1.12)7055950.99 (0.84-1.16)881281.01 (0.69-1.49)
    >6 h/wk4613320.77 (0.65-0.92)4042520.73 (0.60-0.88)37691.35 (0.82-2.21)
        P for trend0.050.030.24
P for interaction = 0.02
Age 14-22§
    0 h/wk3,3652,8711.00 (Reference)2,8142,2051.00 (Reference)4485641.00 (Reference)
    0.1-3 h/wk3,0212,5160.96 (0.89-1.03)2,5581,9320.94 (0.86-1.02)3775111.03 (0.85-1.25)
    3.1-6 h/wk6865780.99 (0.87-1.12)5914470.95 (0.83-1.09)691131.31 (0.93-1.83)
    >6 h/wk5504250.91 (0.79-1.05)4683170.87 (0.74-1.01)55951.40 (0.97-2.02)
        P for trend0.230.050.04
P for interaction = 0.003
Age 22-menopause
    0 h/wk1,4741,1551.00 (Reference)1,2108631.00 (Reference)2292611.00 (Reference)
    0.1-3 h/wk1,8321,5350.99 (0.88-1.10)1,5381,1880.97 (0.85-1.10)2483191.10 (0.84-1.45)
    3.1-6 h/wk3052530.97 (0.80-1.18)2581940.92 (0.74-1.15)41551.21 (0.75-1.94)
    >6 h/wk2011380.83 (0.65-1.05)181990.70 (0.53-0.91)16352.15 (1.11-4.18)
        P for trend0.220.030.04
P for interaction = 0.01
Postmenopausal
    0 h/wk1,2131,0111.00 (Reference)1,0137801.00 (Reference)1702031.00 (Reference)
    0.1-3 h/wk1,8001,4160.91 (0.81-1.02)1,4891,0470.87 (0.76-0.98)2653401.17 (0.89-1.55)
    3.1-6 h/wk5044240.93 (0.79-1.10)4223360.93 (0.78-1.12)71831.02 (0.68-1.52)
    >6 h/wk2922240.86 (0.70-1.05)2591770.80 (0.64-1.00)29421.25 (0.72-2.18)
        P for trend0.130.070.50
P for interaction = 0.68
Past 10 yrs**
    0 h/wk2,0631,7601.00 (Reference)1,7301,3271.00 (Reference)2503491.00 (Reference)
    0.1-3 h/wk3,4662,8670.92 (0.84-1.00)2,8882,1890.93 (0.85-1.02)4675950.89 (0.72-1.10)
    3.1-6 h/wk1,2181,0640.94 (0.84-1.05)1,0458330.94 (0.83-1.06)1472121.00 (0.75-1.33)
    >6 h/wk8676960.87 (0.77-0.99)7605490.86 (0.75-0.98)851271.02 (0.73-1.43)
        P for trend0.050.040.82
P for interaction = 0.38
  • * ORs are adjusted for age, state, mammography, menopausal status, family history of breast cancer, parity, age at first birth, age at menarche, age at menopause, postmenopausal hormone use, education, alcohol, BMI, and weight change since age 18.

  • Activity from age 14 to 1 yr before the reference date.

  • P for interaction determined by inclusion of cross-product terms in logistic models.

  • § Women <22 yr are excluded.

  • Postmenopausal women only.

  • Activity from age at menopause to 1 yr before the reference date (includes postmenopausal women only).

  • ** Activity between 11 yrs and 1 yr before the reference date.