Obstetric history and mammographic density: a population-based cross-sectional study in Spain (DDM-Spain)

Abstract

High mammographic density (MD) is used as a phenotype risk marker for developing breast cancer. During pregnancy and lactation the breast attains full development, with a cellular-proliferation followed by a lobular-differentiation stage. This study investigates the influence of obstetric factors on MD among pre- and post-menopausal women. We enrolled 3,574 women aged 45–68 years who were participating in breast cancer screening programmes in seven screening centers. To measure MD, blind anonymous readings were taken by an experienced radiologist, using craniocaudal mammography and Boyd’s semiquantitative scale. Demographic and reproductive data were directly surveyed by purpose-trained staff at the date of screening. The association between MD and obstetric variables was quantified by ordinal logistic regression, with screening centre introduced as a random effect term. We adjusted for age, number of children and body mass index, and stratified by menopausal status. Parity was inversely associated with density, the probability of having high MD decreased by 16% for each new birth (P value < 0.001). Among parous women, a positive association was detected with duration of lactation [>9 months: odds ratio (OR) = 1.33; 95% confidence interval (CI) = 1.02–1.72] and weight of first child (>3,500 g: OR = 1.32; 95% CI = 1.12–1.54). Age at first birth showed a different effect in pre- and post-menopausal women (P value for interaction = 0.030). No association was found among pre-menopausal women. However, in post-menopausal women the probability of having high MD increased in women who had their first child after the age of 30 (OR = 1.53; 95% CI = 1.17–2.00). A higher risk associated with birth of twins was also mainly observed in post-menopausal women (OR = 2.02; 95% CI = 1.18–3.46). Our study shows a greater prevalence of high MD in mothers of advanced age at first birth, those who had twins, those who have breastfed for longer periods, and mothers whose first child had an elevated birth weight. These results suggest the influence of hormones and growth factors over the proliferative activity of the mammary gland.

First pregnancy events and future breast density: modification by age at first pregnancy and specific VEGF and IGF1R gene variants

“…Other authors have found associations between breast density and birthweight [11, 14] and preterm birth and breast density [11]. While our data were suggestive of relationships between %FGV and these birth characteristics, our findings were neither consistent nor strong.…”

Mammographic density and risk of breast cancer according to tumor characteristics and mode of detection: a Spanish population-based case-control study

“…MD is influenced by classic BC risk factors, such as family history, reproductive factors, benign breast disease, and others [5,6,26]. According to our results, however, adjusting for family history and other possible confounders slightly altered the estimated effect.…”

Dietary Energy Density Is Positively Associated with Breast Density among Young Women

“…While much of the research to date surrounding the contributions of dietary factors to breast density remains mixed, diet may be more influential in premenopausal than postmenopausal women 6, 43, 44 . Breast tissue among premenopausal women is very dynamic because of changes that occur throughout the menstrual cycle and during pregnancy 45–47 . It is thought to be more susceptible to dietary factors such as vitamin D, calcium, and alcohol at this time compared to the postmenopausal years 6, 44, 48 .…”