Pre-diagnosis physical activity and mammographic density in breast cancer survivors

Abstract

Purpose-To investigate the association between physical activity (PA) and mammographic density in the year before diagnosis in a population-based sample of 474 women diagnosed with stage 0-IIIA breast cancer and enrolled in the Health, Eating, Activity, and Lifestyle Study.Methods-We collected information on PA during an interview administered at a baseline visit scheduled within the first year after diagnosis. Participants recalled the type, duration, and frequency of different PAs for the year prior to their diagnosis. Dense area and percent density were estimated, from mammograms imaged approximately one year before diagnosis, as a continuous measure using a computer-assisted software program. Analysis of covariance methods were used to obtain mean density across PA tertiles adjusted for confounders. We stratified analyses by menopausal status and body mass index (BMI) because these factors strongly influence density.Results-We observed a statistically significant decline in mammographic dense area (p for trend = 0.046) and percent density (p for trend = 0.026) with increasing level of sports/recreational PA in postmenopausal women with a BMI ≥ 30 kg/m 2 . Conversely, in premenopausal women with a BMI < 30 kg/m 2 , we observed a statistically significant increase in percent density with increasing level of sports/recreational PA (p for trend = 0.037).Conclusions-Both mammographic dense area and percent density are inversely related to level of sports/recreational PA in obese postmenopausal women. Increasing PA among obese postmenopausal women may be a reasonable intervention approach to reduce mammographic density.

Physical activity and mammographic breast density in a Mediterranean population: The EPIC Florence longitudinal study

“…13 However in agreement with our results, a statistical significant decline in MBD area and percent density with increasing level of prediagnostic recreational PA in obese (BMI 30 kg/m 2 ) postmenopausal women emerged. The collection of information on PA was accurate, extended to several activities and MET hours/week were calculated.…”

“…The methods to assess PA and the components of PA investigated varied widely. Some studies suggested an inverse association between PA and high MBD 12,13 or a positive association with hours of inactivity, 14 while others reported no association. 10,[15][16][17][18] We have carried out a study on 2,001 healthy women to prospectively investigate the influence of baseline individual characteristics related to dietary and life style habits on MBD, as assessed by mammographic examinations (MEs) performed 5 years after the enrolment in the cohort.…”

Recreational Physical Activity and Mammographic Breast Density Characteristics

“…Also similar to our findings, Siozon et al showed that associations between physical activity and breast density were no longer significant after adjusting for BMI (26). Conversely, two studies conducted in distinct populations have reported results consistent with an inverse association between physical activity and breast density (27)(28)(29). In a multi-ethnic study of 474 U.S. women, Irwin et al reported that higher levels of sports/recreational physical activity were associated with lower dense breast area and percent density among obese postmenopausal women [mean (SD) MET-h/wk = 7.8 (12.6)] yet were associated with an increase in percent density among nonobese premenopausal women [mean (SD) MET-h/wk = 19.4 (21.8); ref .…”

“…Significant positive associations between hours of mild exercise per week and both dense area and percent density were observed among well controls in multivariable models; however, given the number of statistical comparisons, lack of other significant associations, and the inconsistency of this finding with all prior studies of physical activity and mammographic density (19,(23)(24)(25)(26)(27)(28)(29), these findings are likely due to chance. Physical activity was not significantly associated with dense breast area before or after adjustment for BMI.…”

“…The Women's Health Initiative (WHI) Observational Study also reported that increased levels of recreational physical activity were related to decreased risk of breast cancer, with an 18% reduction in breast cancer risk from brisk walking for 1.25 to 2.5 h/wk (22). Eight reports to date have described the relationship between physical activity and mammographic breast density: one prospective (19) and four cross-sectional studies (23)(24)(25)(26) reported no statistically significant association; one crosssectional study of Hispanic women found a positive association with physical inactivity (27); and cross-sectional analyses conducted in a study of breast cancer survivors reported an inverse association between pre-diagnosis breast density and physical activity among obese postmenopausal women only (28), with a similar association observed 2 to 3 years after diagnosis (29). The methods of physical activity assessment as well as the characteristics of the study populations have varied widely among these studies, however.…”