Abstract

Minimal residual disease (MRD) refers to the small population of malignant cells that persist after apparently 
successful cancer treatment and remain below the detection limit of conventional diagnostic tools. MRD is a 
major driver of cancer relapse, metastasis, and therapeutic resistance, representing a critical unmet need in 
oncology. Nanotheranostics—integrated nanoscale platforms that combine diagnostic and therapeutic 
functions—have emerged as a promising strategy for the early detection and targeted eradication of MRD. By 
exploiting unique tumor-associated biomarkers, microenvironmental cues, and cellular vulnerabilities, 
nanotheranostic systems enable highly sensitive imaging, real-time disease monitoring, and precision drug 
delivery. This review examines the role of nanotheranostics in addressing the biological and clinical challenges 
of MRD. We discuss the molecular basis of MRD, limitations of current detection and treatment approaches, 
and the design principles underlying nanotheranostic platforms. Emphasis is placed on multifunctional 
nanoparticles capable of simultaneous imaging and therapy, as well as stimulus-responsive systems tailored to 
the MRD niche. Preclinical advances, translational challenges, and future directions toward clinical 
implementation are critically analyzed. Collectively, nanotheranostics represent a transformative approach for 
improving long-term cancer control by enabling earlier intervention and preventing disease recurrence.