Vitamin D deficiency as a risk factor for breast cancer development.

Abstract

10559 Background: Previous studies and meta-analyses have suggested that women with low levels of vitamin D may be at increased risk of breast cancer development and recurrence. The relationship is suspected to be inverse, nonlinear, and predominantly present in postmenopausal women. The purpose of this study was to use the TriNetX platform to determine the magnitude of breast cancer risk increase for women with significant vitamin D deficiency and evaluate the significance of menopause on vitamin D-associated breast cancer risk. Methods: The TriNetX platform was used to generate patient cohorts via International Classification of Disease-10 (ICD-10) codes. All patients were females over 40, had no prior history of breast cancer (C50), and had been diagnosed with menopause (Z78.0). One cohort had less than 20 ng/mL of vitamin D while the other had greater than 30 ng/mL. The cohorts were balanced for age, race, and ethnicity, resulting in 73,659 patients in each arm. They were then evaluated for the future development of breast cancer (C50). Two additional cohorts were created of premenopausal patients aged 40-55 using the same vitamin D parameters and cohort balancing. Results: Postmenopausal women with vitamin D levels below 20 ng/mL had a 45% greater risk of developing breast cancer (risk ratio 1.45, 95% CI (1.38,1.52), p-value <0.0001). (Table) Deficient premenopausal women were also found to be at significantly increased risk although the absolute risk difference was small (relative risk 1.18, 95% CI (1.10,1.27), p-value <0.0001). Conclusions: These results confirm and also quantify the previously-suspected increased breast cancer risk for women who are deficient in vitamin D. The impact of low vitamin D levels on breast cancer risk in premenopausal patients was statistically significant but small in magnitude, while postmenopausal women were found to have approximately 45% higher risk as compared to women who were not deficient. Vitamin D supplementation for all deficient postmenopausal women should be considered. [Table: see text]