Research progress on the mechanisms of tumor-associated macrophages in bladder cancer and the efficacy of immunotherapy

Bladder cancer is a globally prevalent malignancy of the urinary system. In recent years, the application of immune checkpoint inhibitors has significantly improved patient prognosis; however, its treatment still faces challenges such as resistance to immunotherapy and adverse reactions. These issues are partly attributable to the complexity and heterogeneity of the tumor microenvironment (TME). Tumor-associated macrophages (TAMs) are a pivotal component of the TME, exerting profound effects on the development and progression of bladder cancer through mechanisms that regulate inflammatory responses, angiogenesis, and immune evasion. This review summarizes the mechanisms by which TAMs operate in bladder cancer, including their recruitment, polarization, promotion of tumor angiogenesis, and suppression of anti-tumor immune responses. Furthermore, it explores the research progress on TAMs as immunotherapy targets and their therapeutic efficacy, providing new directions for future immunotherapy.