Immune–Inflammatory Crosstalk in Cancer Progression: Translational Insights from Neutrophil-to-Lymphocyte Ratio Studies

Abstract

The interplay between the immune system and cancer is a fundamental determinant of disease progression, therapeutic response, and patient survival. Among various systemic inflammatory markers, the Neutrophil-toLymphocyte Ratio (NLR) has emerged as a robust, cost-effective, and readily accessible prognostic tool. An elevated NLR reflects a shift in the immune-inflammatory balance: a dominance of pro-tumorigenic innate responses (neutrophilia) over anti-tumor adaptive immunity (lymphopenia). This manuscript provides a comprehensive review of the translational mechanisms linking NLR to cancer progression, its role as a prognostic biomarker across various solid tumors, and its emerging utility in predicting responses to modern therapies, including immune checkpoint inhibitors.