Nanotechnology-Based Theranostic Strategies for Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a heterogeneous type of breast cancer characterized by the absence of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression. Because of the lack of ER, PR, and HER2 targets, TNBC is unsuitable for endocrine therapy and HER2-targeted therapy and is associated with a higher risk of early recurrence, distant metastasis, and poorer prognosis than many other breast cancer subtypes, particularly in advanced or metastatic disease. Although surgery, chemotherapy, radiotherapy, and immunotherapy have been used for TNBC treatment, current therapeutic outcomes remain limited by systemic toxicity, high recurrence rates, insufficient tumor selectivity, and acquired drug resistance. Therefore, novel approaches are needed to address these challenges. Nanomaterials with optical, magnetic, catalytic, and porous properties can serve as imaging contrast agents, drug carriers, photosensitizers, nanozymes, radiosensitizers, and multifunctional theranostic platforms. However, the clinical translation of TNBC-oriented nanomedicines remains limited because of insufficient patient stratification, variable tumor accumulation, unclear long-term biosafety, and challenges in scalable manufacturing. To improve the clinical application of nanotechnology in TNBC treatment, it is imperative to integrate nanotechnology with existing clinical diagnosis and treatment methods. This integration may help overcome the limitations of individual diagnostic and therapeutic methods, enhance tumor targeting and radiotherapy sensitivity, reduce cytotoxicity and drug resistance, and maximize the efficiency of multimodal diagnosis and treatment.