Circadian Rhythms in Tumor Regulation: Impacts on Tumor Progression and the Immune Microenvironment

The spatial heterogeneity of tumors has long been a subject of significant interest in oncology. Recent research has revealed that tumors and their microenvironments undergo dynamic changes over time, particularly in the form of periodic circadian rhythms. Disruptions to these rhythms have been recognized as a pivotal factor in the advancement of tumorigenesis. Such disruptions not only induce dysregulation of gene expression within tumor cells, influencing tumor growth, metabolism, the cell cycle, and vascular homeostasis but also facilitate metastasis. Furthermore, they mediate the remodeling of the tumor immune microenvironment, fostering the development of an immunosuppressive milieu. Additionally, the in vivo metabolism and therapeutic responsiveness of tumor treatments—including chemotherapy, targeted therapy, and immunotherapy—have been shown to be modulated by circadian rhythms. This suggests that time-specific drug administration may enhance treatment efficacy, offering novel insights for precision cancer therapy. In this review, we systematically update contemporary research on the impact of circadian rhythms on tumor biology, encompassing both tumor progression and the efficacy of drug therapies. Building upon these insights, we explore the potential for a synergistic approach that integrates the targeting of rhythmic genes with current tumor treatment modalities. We also discuss the feasibility of tailoring tumor therapy to the rhythmic alterations that define in vivo metabolism and the efficacy of specific therapeutic agents, highlighting the significance of rhythm-based strategies in the personalized treatment of tumors and the prevention of associated diseases.