Inflammatory blood markers in breast cancer: a narrative review from early detection to therapy response

Breast cancer remains the most frequently diagnosed malignancy among women worldwide, with early detection and accurate prognostication crucial for improving survival outcomes. While imaging and histopathological analyses are standard diagnostic tools, there is growing interest in cost-effective, minimally invasive biomarkers that can complement existing modalities - particularly in resource-limited settings. This narrative review explores the role of inflammatory blood markers, including neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), and systemic immune-inflammation index (SII), in breast cancer detection, prognosis, and monitoring of therapeutic response. These markers, derived from routine complete blood counts, reflect the systemic immune landscape and are increasingly associated with tumor progression, treatment resistance, and survival. We also highlight the limitations of these markers, particularly their non-specificity, and compare their utility with established diagnostic and molecular techniques. While not diagnostic alone, these inflammatory indices may serve as adjuncts in clinical decision-making and merit further validation in prospective studies.