Cancer is a major killer all around the world. The use of nanoparticles in the detection and treatment of cancer has recently gained widespread attention. The theranostic potential of magnetic nanoparticles (MNPs) as nanomedicine for cancer has been greatly enhanced during the past decade thanks to extensive study. Modern MNPs improve upon their predecessors in several respects, including a greater range of usable, smaller sizes, temperatures easier preparations, lower toxicity and cheaper production costs. MNPs have considerable potential in the medical field due to their unique and superior physical and chemical features. In particular, MNPs could be used as probes in diagnostic imaging and as medication carriers in precision medicine. Although MNPs have great potential in the fields of cancer detection and targeted medication administration, further study is needed to determine how to best reduce their toxicity while simultaneously maximizing their usefulness. MNPs designed for clinical use should be stable enough to serve as tracers or drug delivery vehicles, release drug components selectively at the sites of interest, and pose low danger to human health.