<p>Cancer is a major ongoing threat to human survival and health worldwide due to its high incidence and mortality. Recently, gas therapy has attracted extensive attention as a novel cancer treatment with good biosafety, high efficiency, and few side effects. Given the low solubility and nontargetability of gas molecules, however, various delivery materials have been developed as gas carriers to increase the therapeutic effects of gas treatment. Nanocarriers based on metallic materials have attracted extensive attention because of their stability and biocompatibility. They can undergo gradual degradation to enable the sustained release of bioactive ions, which exert multiple functions, including interference with tumor cell metabolism and immune regulation. This review focuses on the therapeutic mechanisms of various gases used in tumor therapy, including nitric oxide (NO), carbon monoxide (CO), hydrogen sulfide (H₂S), hydrogen (H₂), oxygen (O₂), and sulfur dioxide (SO₂), and related research progress. The targeted delivery of gas donors and the controlled release of reactive gas are achieved through the structural design and functional optimization of gas delivery metallic nanomaterials, which are regulated by multiple exogenous or endogenous stimuli. Furthermore, synergistic combinations of gas therapy with other cancer treatment modalities, such as radiotherapy (RT), phototherapy, and ultrasonic therapy, are comprehensively summarized. Finally, the existing challenges and potential development possibilities of gas-mediated cancer therapy based on metallic nanomaterials are discussed. This review provides insight into the potential development of antitumor strategies to promote the controlled release of gas molecules on-demand for the effective eradication of tumor tissues.</p> Graphical abstract <p></p>