Cancer is usually called continuous and fast growing tumor cells. It is a disease characterized by uncontrolled growth and metastasis by activation of oncogenes, epigenetic modifications, inactivation of tumor suppressors. Treatments are based on researched methods with the aim of minimizing tumor progression, recurrence and mortality. Generally, many treatment methods are applied, especially chemotherapy, radiotherapy and surgical methods. Cytotoxic chemotherapy is most commonly used. Since these chemotherapies target all body cells, they can damage some healthy cells as well as cancer cells. Investigation of the harmful effects of the existing chemotherapy drugs used during the treatment on the cells has an impact on the development of many anticancer agents. Cells die by external influences or by suicide in a controlled manner. There are many reasons for these effects. The drug or drug active ingredient can cause the cell cycle and prevent the cell from multiplying, causing its death. In the same way, it can lead to death of the cell by affecting protein synthesis. In this study, the death effects of four different drug molecules and chemotherapeutic agents on breast cancer (MCF-7) cells were investigated. The effects of death on cells were compared under the microscope. The drug molecules have the ability to induce apoptosis in endothelial cells and cardiomyocytes through the activation of cardiomyopathy, p53 protein, and reactive oxygen species. The structures of the incubated drug-effect cells were examined under the microscope. In general, it has been observed that drug molecules trigger apoptosis, that is, controlled cell death in cancer cells.