This book highlights the most efficient and latest ways to deal with cancer, focusing on IONPs. The book describes some well-designed surface modifications performed through several functional materials over the surface of IONPs, which results in the development of multifunctional IONPs-based delivery nanoplatforms by enhancing solubility, stability, and avoiding side effects on healthy cells. Several types of stimuli-responsive IONPs-based strategies are also discussed. Owing to magnetic, structural, and thermal properties, IONPs themselves can be utilized for magnetic targeting, magnetic hyperthermia, and phototherapy. Significant advancements are presented in IONPs-based immunotherapy, radiotherapy, and sonodynamic therapy for the efficient treatment of cancer. Finally, the book presents RIONs which serve as the parent platform for the development of powerful DMCAs utilized in SPECT/MRI and PET/MRI applications.