7 hours/week of moderate-to-vigorous activity during the past 10 years was associated with 16% reduced risk of postmenopausal breast cancer (RR:0.84; 95%CI:0.76,0.93) compared with inactivity. The association remained statistically significant after adjustment for BMI (RR:0.87; 95%CI:0.78,0.96). Neither moderate-to-vigorous activity during other periods of life nor light intensity activity during any period of life was related to breast cancer risk, and associations did not vary by tumor characteristics. Conclusion A high level of recent, but not historical, physical activity of moderate-to-vigorous intensity is associated with reduced postmenopausal breast cancer risk. More precise recall of recent physical activity than activity in the distant past is one possible explanation for our findings."/>
Light activity | Total | Ages 35-39 years | Past 10 years | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Never/Rarely | <1 hr/wk | 1-3 hrs/wk | 4-7 hrs/wk | >7 hrs/wk | Never/Rarely | <1 hr/wk | 1-3 hrs/wk | 4-7 hrs/wk | >7 hrs/wk | ||
Participants, No. (%) | 118899 | 5189 (4) | 6121 (5) | 20710 (17) | 29018 (24) | 55602 (47) | 5789 (5) | 6811 (6) | 24450 (21) | 32432 (27) | 47827 (40) |
Age at baseline (yrs) | 62.9 | 62.6 | 62.2 | 62.4 | 62.6 | 63.3 | 62.5 | 62.3 | 62.4 | 62.9 | 63.2 |
BMI, current* (kg/m2) | 26.7 | 27.0 | 27.3 | 26.8 | 26.7 | 26.6 | 28.6 | 28.4 | 27.4 | 26.6 | 26.0 |
BMI at age 18* (kg/m2) | 20.9 | 21.1 | 21.1 | 21.0 | 20.9 | 20.8 | 21.3 | 21.1 | 21.0 | 20.8 | 20.8 |
Caucasian (%) | 91.2 | 85.3 | 85.8 | 89.5 | 91.8 | 93.1 | 84.9 | 85.0 | 90.0 | 92.3 | 93.1 |
College education (%) | 31.5 | 31.8 | 33.6 | 35.0 | 34.3 | 28.9 | 27.5 | 29.8 | 34.0 | 33.8 | 29.6 |
Family history of breast cancer† (%) | 13.7 | 13.1 | 13.8 | 13.4 | 13.5 | 13.9 | 13.6 | 13.3 | 13.4 | 13.6 | 13.8 |
Current smoker (%) | 13.4 | 12.6 | 12.8 | 13.3 | 13.1 | 13.7 | 16.7 | 15.1 | 13.7 | 12.9 | 12.9 |
Ever MHT use‡ (%) | 61.7 | 59.0 | 58.7 | 61.6 | 62.5 | 62.1 | 56.9 | 58.3 | 61.8 | 62.8 | 62.0 |
Age at menarche (yrs) | 12.50 | 12.51 | 12.48 | 12.48 | 12.48 | 12.51 | 12.48 | 12.47 | 12.47 | 12.48 | 12.53 |
Age at first birth (yrs) | 22.98 | 22.98 | 23.33 | 23.30 | 23.23 | 22.73 | 22.75 | 23.04 | 23.20 | 23.14 | 22.81 |
Parity (no. of children) | 2.01 | 1.87 | 1.79 | 1.77 | 1.90 | 2.19 | 1.92 | 1.88 | 1.89 | 1.98 | 2.11 |
Age at menopause(yrs) | 47.02 | 47.01 | 47.31 | 47.32 | 47.34 | 47.24 | 46.59 | 47.00 | 47.20 | 47.43 | 47.34 |
Alcohol intake (g/d) | 6.2 | 6.0 | 6.1 | 6.3 | 6.4 | 6.1 | 6.1 | 5.5 | 6.1 | 6.3 | 6.2 |
Moderate-to-vigorous activity | Ages 35-39 years | Past 10 years | |||||||||
Never/Rarely | <1 hr/wk | 1-3 hrs/wk | 4-7 hrs/wk | >7 hrs/wk | Never/Rarely | <1 hr/wk | 1-3 hrs/wk | 4-7 hrs/wk | >7 hrs/wk | ||
Participants, No. (%) | 118899 | 10868 (9) | 10507 (9) | 26715 (23) | 31560 (27) | 37477 (32) | 17028 (14) | 12498 (11) | 29927 (25) | 30231 (25) | 28214 (24) |
Age at baseline (yrs) | 62.9 | 62.8 | 62.5 | 62.5 | 62.7 | 63.4 | 62.9 | 62.5 | 62.7 | 62.9 | 63.1 |
BMI, current* (kg/m2) | 26.7 | 27.6 | 27.3 | 26.8 | 26.5 | 26.4 | 28.7 | 28.0 | 26.9 | 26.0 | 25.4 |
BMI at age 18* (kg/m2) | 20.9 | 21.3 | 21.0 | 20.9 | 20.8 | 20.7 | 21.2 | 21.0 | 20.8 | 20.8 | 20.7 |
Caucasian (%) | 91.2 | 88.0 | 89.1 | 90.9 | 92.6 | 92.6 | 88.7 | 89.7 | 91.4 | 92.7 | 92.4 |
College education (%) | 31.5 | 33.2 | 35.8 | 35.7 | 33.0 | 26.4 | 30.3 | 31.8 | 33.7 | 33.7 | 27.9 |
Family history of breast cancer† (%) | 13.7 | 13.0 | 13.4 | 13.7 | 13.6 | 14.0 | 13.3 | 13.9 | 13.4 | 14.1 | 13.6 |
Current smoker (%) | 13.4 | 12.0 | 12.3 | 12.5 | 13.3 | 14.8 | 15.5 | 14.3 | 13.6 | 12.6 | 12.5 |
Ever MHT use‡ (%) | 61.7 | 56.7 | 60.1 | 63.0 | 63.3 | 61.8 | 57.8 | 60.8 | 62.1 | 64.1 | 61.6 |
Age at menarche (yrs) | 12.50 | 12.38 | 12.48 | 12.48 | 12.49 | 12.55 | 12.40 | 12.46 | 12.48 | 12.52 | 12.56 |
Age at first birth (yrs) | 22.98 | 23.39 | 23.40 | 23.25 | 23.02 | 22.60 | 23.06 | 23.06 | 23.07 | 23.06 | 22.76 |
Parity (no. of children) | 2.01 | 1.74 | 1.81 | 1.89 | 2.02 | 2.22 | 1.88 | 1.95 | 1.99 | 2.04 | 2.09 |
Age at menopause(yrs) | 47.02 | 47.39 | 47.42 | 47.42 | 47.33 | 47.05 | 46.94 | 47.17 | 47.34 | 47.40 | 47.26 |
Alcohol intake (g/d) | 6.2 | 5.7 | 5.9 | 6.3 | 6.5 | 6.2 | 5.8 | 5.8 | 6.1 | 6.4 | 6.5 |