Detection Strategies for HER2 and miR-21 in Breast Cancer: Current Approaches and Future Perspectives- Hybrid Systematic Review and Bibliometric Mapping

Background/Objectives: Breast cancer is still one of the main causes of mortality and morbidity at a global level, highlighting the need to identify robust biomarkers for early diagnosis, prognostic stratification and optimization of therapeutic decisions. Among these biomarkers, HER2 (Human Epidermal Growth Factor Receptor 2) and miR-21 represent the complementary levels of tumor biology, reflecting oncogenic signaling at the protein level and post-transcriptional regulation of gene expression. This hybrid systematic review and bibliometric mapping aims to critically analyze current methods for determining HER2 and miR-21 biomarkers, highlighting their advantages, limitations and clinical applicability, as well as future development directions in the field of precision oncology diagnostics.