Serum 25-hydroxyvitamin D levels among women newly diagnosed with breast cancer at Tikur Anbessa Specialized Hospital, Addis Ababa, Ethiopia.

backgroundBreast cancer (BC) is among the most frequently diagnosed cancers in women, accounting for approximately one in ten new cancer cases annually. The relationship between vitamin D status and BC risk remains unclear; while some observational studies suggest an association, others show no link, and causality is unproven. However, data from sub-Saharan Africa, and specifically Ethiopia, are scarce. This study aimed to assess serum 25-hydroxyvitamin D [25(OH)D] levels in Ethiopian women newly diagnosed with BC compared to healthy controls.

methodsA comparative cross-sectional study was conducted from January to March 2024 at Tikur Anbessa Specialized Hospital, Addis Ababa. Sixty-nine women with newly diagnosed BC and sixty-nine healthy controls were enrolled. Serum 25(OH)D concentrations were measured via electrochemiluminescence immunoassay. Data analysis was performed with SPSS v20. Median differences were evaluated using the Mann–Whitney U test with Hodges–Lehmann estimates and 95% confidence intervals (CI). Logistic regression identified factors associated with BC, and sensitivity analyses were conducted using alternative clinical cut-offs for severe vitamin D deficiency (SVDD).

resultsVitamin D deficiency was prevalent in both groups; however, SVDD (< 10 ng/mL) was significantly more prevalent among BC patients than among controls (26.1% vs. 7.2%, p = 0.006). A significant median difference in 25(OH) D levels was observed between cases and controls (median difference: 2.1 ng/mL; 95% CI: 0.07–4.4; p = 0.043). Serum 25(OH)D levels were also significantly lower in stage IV BC compared with controls and stage I. SVDD was independently associated with BC (adjusted odds ratio = 7.1; 95% CI: 1.7–30.1), and this association remained robust when alternative clinical cut-offs were applied. Reduced sunlight exposure and overweight/obesity were also independently associated with BC.

conclusionSVDD and higher Body Mass Index were significantly associated with BC status. Lower 25(OH)D levels are most pronounced in metastatic (Stage IV) disease. While reduced sunlight exposure was also associated with BC, the direction of these relationships cannot be determined with certainty. These findings highlight an association that warrants further investigation. Further prospective studies with pre-diagnostic 25(OH)D measurements are needed to clarify causality and to determine whether strategies to address VDD may contribute to BC risk reduction.