Lactate, a Spearhead of Cancer Aggressiveness: Metabolic Reprogramming, Immune Suppression, and Metastatic Progression

Reprogramming of cellular energy metabolism is a defining feature of malignancy, characterized by sustained glucose conversion to lactate under aerobic conditions. Once viewed as metabolic waste or a consequence of mitochondrial dysfunction, lactate is now recognized as a multifunctional metabolite that actively drives malignant progression. This review advances the concept of lactate as a spearhead of malignancy that coordinates metabolic adaptation with microenvironmental conditioning, immune suppression, epigenetic regulation, and metastatic dissemination. Beyond its role in metabolism, lactate functions through receptor-mediated signaling and histone lactylation, linking metabolic state to transcriptional programs associated with epithelial–mesenchymal transition, stemness, immune modulation, and therapeutic resistance. Lactate also reshapes the tumor microenvironment by promoting angiogenesis, stromal activation, immune suppression, and invasive behavior, including effects that cannot be explained solely by extracellular acidosis. Together, these observations support lactate as a critical effector of metastatic competence and a strategic target for disrupting multiple cancer hallmarks.