Background

Low 25(OH)D levels are mainly related to breast cancer (BC) risk in postmenopausal women, while the impact of insulin resistance (IR) on BC prognosis is controversial.

Objective

Considering the high prevalence of BC in younger Algerian women, this cross-sectional study analyzed whether vitamin D status and IR are biomarkers for breast tumor status in premenopausal women.

Methods

In 96 women (mean age, 40.96 ± 0.65years) newly diagnosed with BC, tumor status was determined immunohistochemically, classified by molecular subtype, then correlated with body-mass index, total plasma 25(OH)D, insulin and glucose levels and HOMA-IR, using Chi², Student t, Spearman and ANOVA tests and multivariate logistic regression.

Results

A total of 66 of the 96 patients (68.75%) showed vitamin D deficiency (9.74 ng/mL). Overweight and obese patients with HOMA-IR > 2.5, positive for HER2 and with high Ki-67 index had the most severe vitamin D deficiency. There was a significant association between vitamin D deficiency, high Ki-67 index (OR, 14.55; 95% CI: 3.43–82.59; P = 0.00078) and IR (OR, 4.99; 95% CI: 1.27–24.47; P = 0.03), and between IR and HER2-positivity (OR, 3.23; 95% CI: 1.05–10.56; P = 0.04).

Conclusions

Vitamin D deficiency and IR are potential biomarkers for poorer prognosis in BC patients, independently of and/or synergically with high Ki-67 index and HER2-positivity in premenopausal overweight or obese women. The potential relationship of vitamin D receptor gene expression with breast cancer survival in Algerian patients will be investigated in a large cohort.