Objective The aim of this study was to assess the clinical utility of serum circulating microRNA-21 (miR-21) in the early diagnosis of breast cancer (BC), and to compare its diagnostic performance with raditional serum biomarkers, vascular endothelial growth factor (VEGF) and carbohydrate antigen 15-3 (CA15-3). Methods From January 2023 to October 2025, a total of 106 women diagnosed with BC, 69 women with benign breast nodules, and 62 healthy women undergoing routine physical examinations were enrolled at a single institution. Serum levels of miR-21, VEGF, and CA15-3 were measured and compared across groups. Relationships between miR-21 and the traditional markers were analyzed using Spearman correlation analysis. Diagnostic efficacy was assessed via receiver operating characteristic (ROC) curve analysis. Results Relative expression levels of serum miR-21, VEGF, and CA15-3 were significantly elevated in individuals with BC compared to healthy controls (all p 0.05). Serum miR-21 and CA15-3 levels were significantly higher in the BC group than in the benign nodule group (both p 0.05). No significant correlations were observed between miR-21 and VEGF (r = –0.032, p =0.747) or CA15-3 (r = –0.068, p =0.487) in the BC cohort. ROC curve analysis demonstrated that miR-21 had an area under the curve (AUC) of 0.897 for distinguishing BC from healthy individuals, with a sensitivity of 81.10% and a specificity of 98.40% at a cut-off value of 1.36. When differentiating BC from benign nodules, the AUC was 0.842, with a sensitivity of 76.40% and specificity of 98.60% at a cut-off value of 1.52. The diagnostic performance of miR-21 exceeded that of VEGF and CA15-3. Conclusion Serum circulating miR-21 demonstrated significantly elevated expression in patients with BC and presented superior sensitivity and specificity compared to VEGF and CA15-3. These findings highlight miR-21 as a promising non-invasive biomarker for early breast cancer detection, particularly in distinguishing benign from malignant lesions, potentially reducing unnecessary biopsies. However, limitations include a relatively small sample size and single-center design, necessitating validation in larger, multicenter prospective cohorts. Future studies should explore miR-21’s association with molecular subtypes and clinical outcomes to facilitate clinical translation.
Li et al. (Thu,) studied this question.