Table 1

Baseline characteristics according to quintiles of total physical activity in 32,269 women in the Breast Cancer Detection Demonstration Project (BCDDP)*
Characteristic
 Quintile of total physical activity

1
 2
 3
 4
 5

Participants (n)
 6453
 6454
 6441
 6472
 6449
Age (years)
 61.7
 61.1
 61.3
 60.8
 61.0
MET-hours/week (range) †
 105 to 244
 245 to 297
 298 to 339
 340 to 394
 395 to 721
Vigorous physical activity (hours/week)
 0.9
 3.6
 5.4
 10.3
 22.7
Non-vigorous physical activity (hours/week)
 14.8
 32.4
 46.5
 54.5
 59.7
Body mass index (kg/m2)
 25.4
 25.0
 24.9
 24.7
 24.6
Height (inches)
 64.3
 64.2
 64.2
 64.2
 64.1
Ever smoked cigarettes (%)
 46.9
 44.6
 43.4
 42.1
 40.7
Education (% more than high school)
 55.0
 50.0
 46.8
 46.1
 42.0
Age at first birth (years) ‡
 24.0
 23.9
 23.8
 23.9
 23.5
Parity (number of births) ‡
 2.8
 2.8
 2.9
 2.9
 3.0
Age at menarche (years)
 12.7
 12.7
 12.8
 12.8
 12.9
Age at menopause (years)
 50.4
 50.3
 50.2
 50.4
 50.3
History of oral contraceptive use (%)
 33.8
 33.2
 33.4
 32.8
 31.1
Current menopausal hormone therapy (%)
 55.3
 54.7
 55.8
 55.7
 54.1
Family history of breast cancer (%) ¶
 34.0
 35.1
 34.1
 34.4
 33.6
History of benign breast disease (%) §
 55.5
 56.0
 55.4
 55.6
 55.2
Total energy intake (kcal/day)
 1252
 1256
 1266
 1271
 1277
Dietary fat intake (g/day) ||
 46.9
 46.5
 46.3
 46.0
 45.9
Alcohol intake (g/day)
 4.5
 4.4
 4.1
 4.0
 3.6

* All values (except age and range of MET-hours/week) are directly standardised to the age distribution of the cohort at study baseline.

† MET = metabolic equivalent task. The MET value is the caloric need per kilogram of body weight per hour of activity divided by the caloric need per kilogram of body weight per hour at rest.

‡ Among parous women only.

¶Family history of breast cancer includes first- and second-degree relatives with a history breast cancer.

§The BCDDP Follow-up Study includes a disproportionate number of women with benign breast disease due to the design of the original BCDDP.

||Adjusted for total energy intake.

Leitzmann et al. Breast Cancer Research 2008 10:R92   doi:10.1186/bcr2190

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