Cancer immunotherapy is the most promising trend in oncology, focusing on helping or activating the patient's immune system to identify and fight against cancer. In the last decade, interest in metabolic reprogramming of tumor-associated macrophages from M2-like phenotype (promoting tumor progression) to M1-like phenotypes (suppressing tumor growth) as a therapeutic strategy against cancer has increased considerably. Iron metabolism has been standing out as a target for the reprogramming of tumor-associated macrophages to M1-like phenotype with therapeutic purposes against cancer. Due to the importance of the iron levels in macrophage polarization states, iron oxide nanoparticles can be used to change the activation state of tumor-associated macrophages for a tumor suppressor phenotype and as an anti-tumor strategy.