Targeted drug delivery to tumors involves using molecular markers on tumor vessels or cells to concentrate drugs and nanoparticles at the tumor site. Tumor vessels are particularly suitable targets because their surface molecules are accessible to circulating compounds. This approach can enhance drug efficacy, reduce side effects, and improve tumor penetration. Recent advances focus on using molecular markers in tumor vasculature as targets and nanoparticles as delivery vehicles. Tumor vessels express unique proteins not found in normal vessels, making them ideal targets. Phage display has been used to identify tumor-homing peptides that bind to these markers. Examples include F3, which binds to nucleolin, and LyP-1, which binds to p32. These peptides can be used to target drugs or nanoparticles to tumors. Integrins, such as αvβ3 and αvβ5, are also important targets as they are overexpressed in tumor vessels. Tumor endothelial markers, like TEM 8, are also being explored for targeting. Peptides like iRGD, which contain a tissue-penetrating motif, can penetrate tumor tissue and deliver drugs more effectively. These peptides can enhance drug delivery by increasing tumor homing and penetration. Despite these advances, challenges remain, including receptor saturation and limited drug penetration into tumors. Multivalency can enhance targeting efficiency by increasing binding strength. Nanoparticles offer advantages in drug delivery due to their size and ability to carry multiple targeting ligands. Nanoparticle-based targeting has shown promise in improving drug delivery to tumors. For example, iron oxide nanoparticles coated with CREKA peptides can induce clotting in tumor vessels, enhancing drug delivery. Combined with other therapies, such as thermally sensitive liposomes, nanoparticles can improve treatment outcomes. Future research aims to enhance targeting efficiency, improve drug penetration, and develop more effective targeting strategies. The integration of multiple functions into a single nanoparticle system may offer new therapeutic options for cancer treatment. Overall, targeted delivery of drugs and nanoparticles to tumors holds significant potential for improving cancer therapy.Targeted drug delivery to tumors involves using molecular markers on tumor vessels or cells to concentrate drugs and nanoparticles at the tumor site. Tumor vessels are particularly suitable targets because their surface molecules are accessible to circulating compounds. This approach can enhance drug efficacy, reduce side effects, and improve tumor penetration. Recent advances focus on using molecular markers in tumor vasculature as targets and nanoparticles as delivery vehicles. Tumor vessels express unique proteins not found in normal vessels, making them ideal targets. Phage display has been used to identify tumor-homing peptides that bind to these markers. Examples include F3, which binds to nucleolin, and LyP-1, which binds to p32. These peptides can be used to target drugs or nanoparticles to tumors. Integrins, such as αvβ3 and αvβ5, are also important targets as they are overexpressed in tumor vessels. Tumor endothelial markers, like TEM 8, are also being explored for targeting. Peptides like iRGD, which contain a tissue-penetrating motif, can penetrate tumor tissue and deliver drugs more effectively. These peptides can enhance drug delivery by increasing tumor homing and penetration. Despite these advances, challenges remain, including receptor saturation and limited drug penetration into tumors. Multivalency can enhance targeting efficiency by increasing binding strength. Nanoparticles offer advantages in drug delivery due to their size and ability to carry multiple targeting ligands. Nanoparticle-based targeting has shown promise in improving drug delivery to tumors. For example, iron oxide nanoparticles coated with CREKA peptides can induce clotting in tumor vessels, enhancing drug delivery. Combined with other therapies, such as thermally sensitive liposomes, nanoparticles can improve treatment outcomes. Future research aims to enhance targeting efficiency, improve drug penetration, and develop more effective targeting strategies. The integration of multiple functions into a single nanoparticle system may offer new therapeutic options for cancer treatment. Overall, targeted delivery of drugs and nanoparticles to tumors holds significant potential for improving cancer therapy.