Associations of mammographic dense and nondense areas and body mass index with risk of breast cancer

Am J Epidemiol. 2014 Feb 15;179(4):475-83. doi: 10.1093/aje/kwt260. Epub 2013 Oct 28.


Mammographic density measurements are associated with risk of breast cancer. Few studies have investigated the concurrent associations of mammographic dense and nondense areas, body mass index (weight (kg)/height (m)(2)), and ages at mammogram and diagnosis with breast cancer risk. We conducted a matched, case-control study nested within the Melbourne Collaborative Cohort Study (cohort recruitment in 1990-1994 and follow-up until 2007) to estimate the associations between these factors and breast cancer risk under alternative causal models. Mammographic dense area was positively associated with risk, and the strength of this association was only slightly influenced by the choice of the causal model (relative risk per 1 standard deviation = 1.50, 95% confidence interval: 1.32, 1.70). Mammographic nondense area was inversely associated with risk under the assumption that fat in the body and fat in the breast cause breast cancer through independent mechanisms (relative risk per 1 standard deviation = 0.75, 95% confidence interval: 0.65, 0.86), whereas it was not associated with risk under the assumption that they are both proxies of adiposity. Knowledge about the biological mechanisms regulating the role played by mammographic nondense area and body fat on breast cancer risk is essential to better estimate their impacts on individual risk.

Keywords: breast neoplasms; mammographic density; prospective studies; risk.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Body Mass Index*
  • Breast / anatomy & histology*
  • Breast Density
  • Breast Neoplasms / diagnostic imaging*
  • Breast Neoplasms / epidemiology
  • Breast Neoplasms / pathology
  • Case-Control Studies
  • Causality
  • Confounding Factors, Epidemiologic
  • Female
  • Humans
  • Linear Models
  • Mammary Glands, Human / abnormalities*
  • Mammography
  • Risk