Physical activity in relation to mammographic density in the dutch prospect-European prospective investigation into cancer and nutrition cohort.
BACKGROUND
Evidence accumulates that physical inactivity is one of the few modifiable risk factors for breast cancer. The mechanism through which physical inactivity affects breast cancer risk is not clear. The study aim was to investigate the association between physical activity and breast density because mammographic density is strongly associated with breast cancer risk.


METHODS
We did a cross-sectional study in 620 women, of ages 49 to 68 years and participants of the Dutch Prospect-European Prospective Investigation into Cancer and Nutrition cohort. A self-administered questionnaire was used to obtain information on duration and intensity of physical activity (recreational, household, and occupational) during the year preceding study recruitment. A total activity index (inactive, moderately inactive, moderately active, and active) was estimated by combining all activity types. Percent and absolute breast density were determined on screening mammograms using a computer-aided method. Multivariate linear regression was used to examine the association between physical activity and breast density.


RESULTS
Mean percent density was 35.3% [95% confidence interval (95% CI), 31.8-38.8] for the inactive category compared with 36.1% (95% CI, 33.0-39.2) for the active category. Mean absolute density values for the inactive and active category were 45.8 cm(2) (95% CI, 40.9-50.7) and 42.6 cm(2) (95% CI, 38.3-47.0), respectively. Subgroup analysis for postmenopausal women showed similar results, as did separate analyses for recreational and household activity.


CONCLUSIONS
The result does not support a relation between current physical activity and mammographic density in postmenopausal women.
Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, the Netherlands.
Karijn P M
KP
Suijkerbuijk
Fränzel J B
FJ
Van Duijnhoven
Carla H
CH
Van Gils
Paulus A H
PA
Van Noord
Petra H M
PH
Peeters
Christine M
CM
Friedenreich
Evelyn M
EM
Monninkhof
D000328:Adult; D017677:Age Distribution; D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000517:prevention & control; D015331:Cohort Studies; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008019:Life Style; D008327:Mammography; D008875:Middle Aged; D009043:Motor Activity; D009426:Netherlands / Q000453:epidemiology; D009752:Nutritional Status; D011322:Primary Prevention / Q000379:methods; D011336:Probability; D011379:Prognosis; D011446:Prospective Studies; D012016:Reference Values; D018570:Risk Assessment; D012680:Sensitivity and Specificity