Optimizing Cancer Treatment: A Comprehensive Review of Active and Passive Drug Delivery Strategies.

Nanocarriers as powerful tools for delivering drugs to tumors provide new strategies for cancer treatment. These delivery systems encompass a diverse variety of structures, including polymeric nanoparticles (NPs), liposomes, dendrimers, micelles, and inorganic NPs such as gold and silica. Each type exhibits distinct physicochemical advantages that contribute to stability, drug-loading capacity, and targeting efficacy. Engineered nanocarriers can be utilized for the active targeting of tumor-specific receptors or for passive targeting of tumors via the enhanced permeability (EPR) and retention effect, a characteristic of abnormal tumor vasculature. This targeting approach enables the precise delivery of the therapeutic agents at tumor sites, increasing drug efficacy while minimizing exposure to healthy tissues. The benefits of these strategies include reduced systemic adverse effects, improved bioavailability, and an optimized therapeutic index. This review examines both active and passive drug delivery systems, with a special focus on the characteristics of the EPR effect.