Bone mineral density and mammographic density in Mexican women

Abstract

Background Bone mineral density (BMD) is a putative marker for lifetime exposure to estrogen. Studies that have explored whether BMD is a determinant of mammographic density (MD) have observed inconsistent results. Therefore, we examined this potential association in a sample of women (N=1,516) from the clinical sub-cohort in the Mexican Teachers’ Cohort (N=115,315). Methods We used multivariable linear regression to assess the association between quartiles of BMD and percent MD, as well as total dense and non-dense area of the breast, stratified by menopausal status. We also examined the associations by body mass index (BMI) (<30kg/m2,, ≥30kg/m2). Results Overall, there was no association between BMD and MD among premenopausal women. However, when we stratified by BMI, there was a modest inverse association between BMD and percent MD (difference between extreme quartiles= −2.8, 95%CI: −5.9, 0.27, p-trend=0.04) among women with BMI <30 kg/m2, but a positive association among obese women (comparable difference=5.1, 95%CI: 0.02, 10.1, p-trend=0.03; p-interaction<0.01). Among postmenopausal women, BMD and percent MD were positively associated after adjustment for BMI (p-trend<0.01). Postmenopausal women in the highest two quartiles of BMD had 4–5 percentage point higher percent MD compared to women in the lowest quartile. The association did not differ by BMI in postmenopausal women (p-interaction=0.76). Conclusion Among obese premenopausal women as well as postmenopausal women, BMD was positively associated with percent MD. Among leaner premenopausal women, BMD and percent MD were modestly inversely associated. These findings support the hypothesis that cumulative exposure to estrogen (as measured by BMD) may influence MD.

Is There an Association Between Bone Mineral Density and Mammographic Density? A Systematic Review

“…45 In addition, a recently published study reported no association overall, but a positive association between BMD and percent mammographic density among obese women, and an inverse association among leaner women. 34 This suggests a complex association. Nevertheless, studies evaluating the association of BMD with percent mammographic density have not stratified their analyses by BMI, except for one conducted among Kuwaiti women.…”

“…Only three studies have investigated the association of BMD at other sites, including ribs, arms, leg, and whole body, with mammographic density 28,33,34 and two studies reported no associations overall. However, Sung et al observed a positive association of BMD at the legs with mammographic density among premenopausal women (b = 0.59, p < 0.05) 33 ( Table 3).…”

“…Furthermore, if mammographic density is associated with BMD, knowing a woman's breast density might have some utility in predicting BMD, and possibly future fracture risk since BMD is a strong predictor of future fracture risk. 26 The few studies that have investigated the association of BMD with percent mammographic density, [27][28][29][30][31][32][33][34] have produced conflicting results, and no review of the topic has been undertaken. To extend knowledge on the association of BMD with percent mammographic density, we conducted a systematic review of published studies.…”