Cancer is still one of the most common diseases in the world and the leading cause of death. So far, various methods have been offered for cancer treatment, the most common of which are chemotherapy, surgery and radiation therapy, which have high side effects. Therefore, the need to develop an alternative treatment method has the highest priority. In this research, the photothermal therapy method in cancer treatment has been investigated. The photothermal therapy method can be very accurate and minimally invasive due to the direct, intense light radiation to the target tumour. In this research, photothermal therapy is combined with chemotherapy, and the therapeutic agents in this research include a photothermal therapy agent that receives laser light and converts it into heat to destroy cancer cells and a drug carrier. In which the chemotherapy drug is loaded. The aim of this research is to investigate the effect of photothermal therapy on the melanin-calcium carbonate combination as a nanocomposite and to investigate the chemotherapeutic effect of the drug doxorubicin loaded in the nanocomposite. Natural melanin nanoparticles have been used as photothermal therapy agents, and calcium carbonate nanoparticles have been used as doxorubicin drug carriers. An 808 nm laser with a power of 1000 mW was used as a light source, and the effects of photothermal therapy were observed and recorded with a temperature sensor. To check the chemotherapy effect, the optimal amount of drug was loaded into the nanocomposite, and then its accuracy was measured by ultraviolet-visible spectroscopy. By examining the analyses carried out, the surface area and pore volume of the manufactured nanocomposite were found to be 28.571 m2g-1 and 0.178 cm3g-1, respectively. Also, the effect of photothermal therapy on the manufactured nanocomposite was 19.6 degrees, and the amount of doxorubicin drug loading in the nanocomposite was obtained at an optimal amount of about 48%, which proves the effecti