Biocompatible Tantalum Nanoparticles as Radiosensitizers for Enhancing Therapy Efficacy in Primary Tumor and Metastatic Sentinel Lymph Nodes.

Metastasis of breast carcinoma is commonly realized through lymphatic circulation, which seriously threatens the lives of breast cancer patients. Therefore, efficient therapy for both primary tumor and metastatic sentinel lymph nodes (SLNs) is highly desired to inhibit cancer growth and metastasis. During breast cancer treatment, radiotherapy (RT) is a common clinical method. However, the efficacy of RT is decreased by the radioresistance to a hypoxic microenvironment and inevitable side effects for healthy issues at high radiation doses. Considering the above-mentioned, we provide high biocompatible poly(vinylpyrrolidone) coated Ta nanoparticles (Ta@PVP NPs) for photothermal therapy (PTT) assisted RT for primary tumor and metastatic SLNs. On the one hand, for primary tumor treatment, Ta@PVP NPs with a high X-ray mass attenuation coefficient (4.30 cm/kg at 100 keV) can deposit high radiation doses within tumors. On the other hand, for metastatic SLNs treatment, the effective delivery of Ta@PVP NPs from the primary tumor into SLNs is monitored by computed tomography and photoacoustic imaging, which greatly benefit the prognosis and treatment for metastatic SLNs. Moreover, Ta@PVP NPs-mediated PTT could enhance the RT effect, and immunogenic cell death caused by RT/PTT could induce an immune response to improve the therapeutic effect of metastatic SLNs. This study not only explores the potential of Ta@PVP NPs as effective radiosensitizers and photothermal agents for combined RT and PTT but also offers an efficient strategy to cure both primary tumor and metastatic SLNs in breast carcinoma.