Association between oxidative stress markers and antioxidant vitamins C and D in Iraqi women with breast cancer: A cross-sectional study

Objective: To evaluate the relationship between oxidative stress (measured by malondialdehyde, MDA) and antioxidant vitamins C and D in the incidence and progression of breast cancer among Iraqi women. Methods: This cross‑sectional study was conducted at Kirkuk Oncology Centre from December 2025 to March 2026. It included 90 women with histologically confirmed breast cancer (stages I–IV) and 45 age‑matched healthy controls. Fasting serum samples were analysed for MDA, superoxide dismutase (SOD), glutathione peroxidase (GPx), vitamin C and vitamin D using ELISA and the Roche Cobas system. Results: Breast cancer patients had significantly lower mean vitamin C (1.00 ± 0.20 vs. 1.32 ± 0.23 mg/dL, p<0.001) and vitamin D (13.19 ± 4.35 vs. 23.26 ± 5.18 IU/L, p<0.001) levels than controls, and significantly higher MDA (26.27 ± 6.34 vs. 18.20 ± 5.76 ng/mL, p<0.001). Vitamin D levels decreased progressively from stage I (14.9 ± 4.1) to stage IV (10.37 ± 3.85) (p=0.006). A moderate negative correlation was observed between vitamin D and MDA (r = –0.45, p=0.009). Vitamin C levels did not differ significantly across cancer stages. Conclusion: Elevated oxidative stress and reduced antioxidant vitamins C and D are associated with breast cancer in Iraqi women. Vitamin D shows an inverse relationship with cancer stage, suggesting a possible role in disease progression. Prospective studies are needed to establish causality.