Cancer metastasis accounts for the high mortality of many types of cancer. Owing to the unique advantages of high specificity and minimal invasiveness, photothermal therapy (PTT) has been evidenced with great potential in treating cancer metastasis. In this review, we outline the current approaches of PTT with respect to its application in treating metastatic cancer. PTT can be used alone, guided with multimodal imaging, or combined with the current available therapies for effective treatment of cancer metastasis. Numerous types of photothermal nanotherapeutics (PTN) have been developed with encouraging therapeutic efficacy on metastatic cancer in many preclinical animal experiments. We summarize the design and performance of various PTN in PTT alone and their combinational therapy. We also point out the lacking area and the most promising approaches in this challenging field. In conclusion, PTT or their combinational therapy can provide an essential promising therapeutic modality against cancer metastasis.

Cancer metastasis leads to high mortality of breast cancer and is difficult to treat because of the poor delivery efficiency of drugs. Herein, we report the wrapping of a drug-carrying liposome with an isolated macrophage membrane to improve delivery to metastatic sites. The macrophage membrane decoration increased cellular uptake of the emtansine liposome in metastatic 4T1 breast cancer cells and had inhibitory effects on cell viability. In vivo, the macrophage membrane enabled the liposome to target metastatic cells and produced a notable inhibitory effect on lung metastasis of breast cancer. Our results provide a biomimetic strategy via the biological properties of macrophages to enhance the medical performance of a nanoparticle in vivo for treating cancer metastasis.

The tumor growth and metastasis is the leading reason for the high mortality of breast cancer. Herein, it is first reported a deep tumor‐penetrating photothermal nanotherapeutics loading a near‐infrared (NIR) probe for potential photothermal therapy (PTT) of tumor growth and metastasis of breast cancer. The NIR probe of 1,1‐dioctadecyl‐3,3,3,3‐tetramethylindotricarbocyanine iodide (DiR), a lipophilicfluorescent carbocyanine dye with strong light‐absorbing capability, is entrapped into the photothermal nanotherapeutics for PTT application. The DiR‐loaded photothermal nanotherapeutics (DPN) is homogeneous nanometer‐sized particles with the mean diameter of 24.5 ± 4.1 nm. Upon 808 nm laser irradiation, DPN presents superior production of thermal energy than free DiR both in vitro and in vivo. The cell proliferation and migration activities of metastatic 4T1 breast cancer cells are obviously inhibited by DPN in combination with NIR irradiation. Moreover, DPN can induce a higher accumulation in tumor and penetrate into the deep interior of tumor tissues. The in vivo PTT measurements indicate that the growth and metastasis of breast cancer are entirely inhibited by a single treatment of DPN with NIR irradiation. Therefore, the deep tumor‐penetrating DPN can provide a promising strategy for PTT of tumor progression and metastasis of breast cancer.