A suitable polymer-based drug delivery system for achieving sustained release of a water-insoluble anticancer drug is the use of polymeric nanoparticles or micelles. Polymeric nanoparticles are small, biodegradable particles made from polymers such as poly lactic-co-glycolic acid PLGA , poly caprolactone PCL , or poly ethylene glycol PEG . These polymers can encapsulate the water-insoluble anticancer drug, protecting it from degradation and allowing for controlled release over time.Polymeric micelles, on the other hand, are self-assembled nanostructures formed by amphiphilic block copolymers. These copolymers have both hydrophilic and hydrophobic segments, allowing them to form a core-shell structure in an aqueous environment. The hydrophobic core can encapsulate the water-insoluble anticancer drug, while the hydrophilic shell provides stability and biocompatibility.Both polymeric nanoparticles and micelles can be designed to achieve sustained release of the encapsulated drug by controlling factors such as polymer composition, molecular weight, and drug loading. Additionally, these systems can be functionalized with targeting ligands to enhance the specificity of drug delivery to cancer cells, reducing side effects and improving therapeutic efficacy.