Reactive Oxygen Species (ROS) are reactive molecules containing oxygen, such as superoxide (O2•-), hydrogen peroxide (H2O2), and hydroxyl radicals (•OH). These molecules are typically produced as byproducts of cellular metabolism, particularly within mitochondria. While ROS are essential for normal cellular functions like signaling and defense against pathogens, their dysregulation can contribute to cancer development and progression. At high levels, ROS can induce oxidative stress, leading to apoptosis (programmed cell death) or necrosis in cancer cells. This property makes ROS a target for therapies aimed at increasing ROS levels in tumors to induce cancer cell death. ROS can modulate the immune response, influencing the activity of various immune cells, including T cells and macrophages, which can either promote or inhibit tumor growth depending on the context. Photothermal Therapy (PTT) is a minimally invasive treatment that involves the use of photosensitizers, such as nanoparticles, that can absorb near-infrared (NIR) light and convert it into heat. This localized heat can destroy cancer cells directly and also stimulate anti-tumor immune responses, making PTT a promising approach in immuno-oncology. When photosensitizers are exposed to NIR light, they generate heat, leading to hyperthermia (elevated temperatures) in the tumor tissue. This can cause direct thermal damage to cancer cells, leading to their destruction. The heat generated during PTT can cause the release of tumor antigens and danger-associated molecular patterns (DAMPs) from dying cancer cells. These molecules can enhance the presentation of tumor antigens to the immune system, promoting an anti-tumor immune response. PTT can alter the TME, making it more conducive to immune cell infiltration. This can enhance the effectiveness of other immunotherapies, such as ICIs, by making tumors more "visible" to the immune system. ROS and PTT are both emerging areas in immuno-oncology that offer unique mechanisms for targeting and destroying cancer cells while potentially enhancing the immune response against tumors. While challenges remain, these therapies represent promising avenues for developing more effective and less invasive cancer treatments, particularly when combined with other immunotherapeutic approaches. • ROS | sonodynamic therapy (SDT) Sonodynamic Therapy (SDT) is a non-invasive treatment modality that uses low-intensity ultrasound in combination with sonosensitizers to generate ROS and induce selective cytotoxic effects in tumor cells. SDT has emerged as a promising approach in cancer therapy due to its ability to penetrate deep tissues and its potential to be combined with immunotherapies.