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Physical activity does not impact mammographic density
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Physical activity did not appear associated with mammographic density among pre- and postmenopausal women, according to results of a Danish prospective cohort study presented at the 10th European Breast Cancer Conference.
These results suggest that the protective effect of physical activity on breast cancer risk is not mediated by mammographic density, according to the researchers.
Shadi Azam, MSc, researcher at University of Southern Denmark, in Esbjerg, Denmark, and colleagues evaluated the association between mammographic density and physical activity among 1,202 premenopausal and 4,501 postmenopausal women who participated in the Danish Diet, Cancer and Health cohort between 1993 and 1997. Women underwent mammographic screening in Copenhagen between 1993 and 2001.
The researchers assessed participation in and hours spent per week on sports, walking, cycling, gardening and occupational physical activity via a baseline questionnaire. All activities were grouped according to number of hours spent on the activity per week (none, up to 2 hours, 4 hours and more than 4 hours).
More than half (56.3%) of study participants had mixed or dense breasts, as determined independently by two radiologists and then validated using the Breast Imaging and Data System assessment tool.
Nearly all women reported walking (92.7%), 70.1% cycled, 52.2% reported gardening and 47.5% participated in sports.
Results showed women who participated in sports (OR = 1.17; 95% CI, 1.05-1.3) or cycled (OR = 1.19; 95% CI, 1.06-1.33) were more likely to have mixed or dense breasts.
Conversely, results from a fully adjusted model showed a weak association between gardening and mammographic density (OR = 1.06; 95% CI, 0.94-1.18). There was no association between walking and mammographic density (OR = 0.98; 95% CI, 0.79-1.22).
Neither occupational physical activity nor the time spent on activities demonstrated a dose–response relationship with mammographic density.
“In light of our findings, we believe that further studies should now be focused on other mechanisms that might explain the association between physical activity and breast cancer risk,” Azam said in a press release. “We would be very interested to see our research replicated in another large study group in order to provide further certainty. ... We would encourage all women to undertake the lifestyle changes that can reduce their risk of breast cancer.” – by Jennifer Southall
Reference: Azam S, et al. Abstract 13. Presented at: 10th European Breast Cancer Conference; March 9-11, 2016; Amsterdam.
Disclosure: The researchers report no relevant financial disclosures.