Nanomedicines inhibiting tumor metastasis and recurrence and their clinical applications

Tumor metastasis and recurrence is one of the biggest problems in curing cancers. Due to the difficulty in complete removal of the primary tumor in traditional surgeries and the poor drug delivery efficiency of traditional chemotherapy, the residual tumor cells/tissues may further develop and result in tumor recurrence and/or distant metastasis. Nanoparticles with targeting probes and payload chemo-drugs are expected to conquer this problem, because they can efficiently accumulate at tumor sites to effectively inhibit the proliferation and metastasis of the primary tumor cells by themselves or via combination with other therapies, such as photothermal therapy, photodynamic therapy, chemotherapy, gene silencing, gene editing, etc. Meanwhile, they can also capture circulating tumor cells (CTCs), concentrate in targeted organs/lymph nodes that were invaded by metastatic tumor cells, and inhibit tumor metastasis and recurrence. From material science point of view, the functions of nanomedicines could be roughly divided into different categories, such as serving as nanocarriers for delivery of theranostic probes/chemotherapy drugs, as image contrast enhancers/radiosensitizers, diagnostic agents, or therapeutic agents. From a disease point view, tumor treatment can be roughly divided into different stages, including diagnosis, destruction of primary tumors, prevention of metastasis/recurrence, and clinical applications. In this paper, we review the use of nanomaterials in the treatment of tumors with a focus on those related to the inhibition of tumor metastasis/recurrence as well as clinical applications. We analyze the mechanisms and methods of using functional nanoparticles to destroy primary tumors and explore the abilities of functional nanoparticles on the inhibition of growth, spread, and recurrence of metastatic tumors. We also summarize the literature reported ongoing oncological trials in clinics using nanomedicines. Finally, we offer analysis and an outlook on the current research status, and highlight challenges and perspectives for the future development of nanomedicines.