Physical Activity, Mammographic Density, and Age-Related Lobular Involution Among Premenopausal and Postmenopausal Women

Menopause. 2015 Sep;22(9):964-75. doi: 10.1097/GME.0000000000000433.

Abstract

Objective: Physical activity may protect against breast cancer by modulating breast tissue composition. We evaluated the association of physical activity with two visual assessments of breast tissue composition-percentage of mammographic density (a radiologic observation) and age-related lobular involution (a histologic assessment).

Methods: Among 164 premenopausal and postmenopausal women with breast cancer, physical activity (household, occupational, and recreational) performed during the year preceding the diagnosis was evaluated using a validated questionnaire. Percentage of mammographic density was assessed in the contralateral breast by a computer-assisted method. Age-related lobular involution was assessed in normal breast tissue on H&E-stained slides. Multivariate generalized linear models were used to assess associations by quartiles of physical activity.

Results: Overall, we observed no significant association between total physical activity and percentage of mammographic density or degree of lobular involution. However, occupational physical activity was significantly positively associated with the predominant type I/no type III lobules among premenopausal women (last quartile: prevalence ratio [PR], 5.92; P(trend )= 0.04). Although total physical activity was positively associated with the predominant type I/no type III lobules among premenopausal women (last quartile: PR, 2.61; P(trend) = 0.08), an inverse association was observed among postmenopausal women (last quartile: PR, 0.44; P(trend) = 0.01). Higher levels of household physical activity were significantly associated with higher prevalence of lower mammographic density and complete involution among postmenopausal women (last quartile: PR, 1.21; P(trend) = 0.01).

Conclusions: Physical activity may be associated with less dense and more involuted breasts. Physical activity's effect on mammographic density or age-related lobular involution may mediate, in part, its protective effect against breast cancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Breast Neoplasms / diagnostic imaging
  • Breast Neoplasms / epidemiology*
  • Carcinoma, Lobular / diagnostic imaging
  • Carcinoma, Lobular / epidemiology*
  • Female
  • Humans
  • Mammography
  • Middle Aged
  • Motor Activity*
  • Postmenopause
  • Premenopause
  • Prevalence
  • Quebec / epidemiology