Table 4.

Multivariate RR (95% CI) for the association between physical activity and breast cancer incidence among postmenopausal women according to BMI, MHT use, and family history of breast cancer

No. casesPhysical activity (times per week)
PtrendPheterogeneity
Inactive<11-23-4≥5
BMI (kg/m2)
    ≥25.03,7871.0 (Reference)0.98 (0.89-1.08)0.98 (0.90-1.08)0.92 (0.84-1.01)0.86 (0.77-0.96)0.0030.07
    <25.02,8221.0 (Reference)1.01 (0.92-1.11)0.97 (0.89-1.05)0.99 (0.92-1.08)0.95 (0.87-1.05)0.64
MHT use
    Ever use4,0731.0 (Reference)1.03 (0.93-1.15)1.00 (0.90-1.10)1.00 (0.92-1.10)0.97 (0.88-1.08)0.340.002
    Never use2,5281.0 (Reference)0.95 (0.84-1.08)0.88 (0.79-0.99)0.86 (0.77-0.96)0.76 (0.67-0.86)<0.001
Family history
    Family history1,1931.0 (Reference)0.99 (0.83-1.19)0.92 (0.78-1.08)0.75 (0.64-0.89)0.75 (0.62-0.91)<0.0010.003
    No family history5,1241.0 (Reference)0.99 (0.90-1.09)0.95 (0.87-1.03)0.98 (0.90-1.06)0.88 (0.81-0.97)0.03
  • NOTE: Multivariate models used age as the underlying time metric and were adjusted for race/ethnicity (White, Black, Hispanic, Asian/Pacific Islander/American Indian), education level (<12 years or high school equivalent, 12 years or high school equivalent, post-high school vocational or technical training, some college, college graduate, postgraduate), smoking status (nonsmoker, former, current), family history of breast cancer (no, yes), menopausal hormone use (never, current, past), age at first birth (nulliparous, <20, 20-24, 25-29, ≥30 years), age at menarche (<13, 13-14, ≥15 years), age at menopause (<40, 40-44, 45-49, 50-54, ≥55 years), parity (number of children: 0, 1-2, ≥3), and alcohol intake (g/d; quintiles adjusted for total energy intake).