The specialized book "Utilization of Inactivated S. aureus Bacteria" by Marta Kwiatkowska discusses the innovative application of inactivated Staphylococcus aureus bacteria for targeted drug delivery in cancer treatment. Given the challenges associated with conventional treatment methods, particularly in advanced tumors, a novel approach is presented that involves the use of Doxorubicin in combination with a carrier system made of dead bacteria, gold nanoparticles, and a thiol derivative of hyaluronic acid. The research focuses on the cytotoxic properties of this system and its effect on the A549 cancer cell line in vitro. The results show promising approaches to reducing the viability of tumor cells by inhibiting their proliferation, opening new perspectives for cancer therapy.