Serum 25−Hydroxyvitamin D3 ((25(OH)D3) and Mammography Density Among Mexican Women

Low levels of vitamin D and high mammography density (MD) have been associated with higher risk of breast cancer. Although some evidence suggested an inverse association between vitamin D intake and MD, no studies have investigated this association among women in Latin American countries. We examined whether serum 25−hydroxyvitamin D3 ((25(OH)D3) levels were related to MD in a cross‐sectional study nested within the Mexican Teacher's Cohort (ESMaestras). This study includes 491 premenopausal women. MD was assessed using a computer‐assisted method. Serum 25(OH)D3 levels were measured by liquid chromatography/tandem mass spectrometry. Linear regression was used to estimate the association of different measures of MD with serum 25(OH)D3. Median serum 25(OH)D3 level was 27.3 ± 6.93 ng/ml. 8.35% of women had 25(OH)D3 levels < 20 ng/ml. Season was associated with 25(OH)D3 (P <0.001). Preliminary analyses showed that body mass index (BMI) and total physical activity were significantly related to serum 25(OH)D3 (r = −0.109, P =0.019 and r =0.095, P=0.003, respectively). In the multivariate linear regression, no significant association was observed overall. However, in stratified analyses, higher serum 25(OH)D3 levels (蠅 27.3 ng/ml) were significant related to percent MD in non‐obese women (BMI<30) (β = −0.560, P=0.016). Our preliminary results suggest an inverse association between higher serum 25(OH)D3 levels (> median) and MD in premenopausal non‐obese women.