Vitamin D Status and Association of Genetic Polymorphism to Risk of Breast Cancer in Ethiopia

Emerging evidence associates vitamin D deficiency and vitamin D receptor () genetic variations with risk for breast cancer. This study investigated the prevalence of vitamin D deficiency and its association with tumor characteristics and the implications of genetic variations for risk of breast cancer in Ethiopia. This unmatched case⁻control study involved 392 female breast cancer patients and 193 controls. The plasma 25-hydroxyvitamin D (25(OH)D₃) level was quantified in chemotherapy-naïve ( = 112) and tamoxifen-treated patients ( = 89). Genotyping for the common variant alleles rs7975232 (I), rs2228570 (I), and rs731236 (I) was done. Eighty-six percent of the patients were vitamin D deficient (<50 nmol/L). Chemotherapy-naïve breast cancer patients had a higher prevalence of vitamin D deficiency (91.9% vs. 78.3%) compared to the tamoxifen-treated group ( < 0.001). The prevalence of severe vitamin D deficiency (<25 nmol/L) was significantly higher in chemotherapy-naïve (41.1%) than tamoxifen-treated (11.2%) patients. Vitamin D deficiency was not significantly associated with tumor characteristics or genotype. The rs2228570 genotype was associated with increased risk of breast cancer (OR = 1.44, 95% confidence interval = 1.01-2.06). Our result indicates that rs2228570 might be a moderate risk factor for breast cancer development in the Ethiopian population. The high prevalence of severe vitamin D deficiency in treatment-naïve breast cancer patients indicates the need for nutritional supplementation of vitamin D at the time of chemotherapy initiation.