Association Between Vitamin D Status and Breast Cancer Among Iraqi Women: A Case–Control Study

Abstract

Aim: To investigate the association between serum 25-hydroxyvitamin D [25 (OH) D] levels and breast cancer in females living in Najaf, Iraq.

Methods: A case-control study was carried out, consisting of 116 women (56 breast cancer patients and 60 controls with no cancer diagnosis). The 25(OH)D level was determined and categorized as low (below 12 ng/mL), insufficient (12–<20 ng/mL), and adequate (20 ng/mL or higher). Multivariable logistic regression was employed to assess the association between vitamin D with breast cancer, adjusting for age and body mass index (BMI).

Results: Mean serum 25(OH)D concentration was substantially lower among cases than controls (9.46 ± 5.85 vs. 23.42 ± 12.31 ng/mL). Vitamin D deficiency was observed in 78.6% of cases compared with 16.7% of controls, whereas adequate concentrations were observed in 3.6% and 46.7%, respectively. The distribution of vitamin D categories differed significantly between groups (χ²(2) = 48.36, p < 0.001; Cramér’s V = 0.646). Compared with adequate vitamin D status, deficiency was associated with markedly higher odds of breast cancer (adjusted OR = 56.91, 95% CI: 10.75–301.19, p < 0.001), while generally inadequate status was also significantly associated with higher odds (adjusted OR = 11.10, 95% CI: 1.90–64.88, p = 0.0075).

Conclusion: The association between low levels of 25(OH)D and breast cancer was strong in this study population and the association remained statistically significant following adjustment for age and BMI. Further, larger studies are needed to elucidate the time course and possible associated with vitamin D and the development of breast cancer.