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An important problem in the treatment of cancer patients is the high incidence of bone fractures. According to the treatment protocols, the vast majority of such patients require long-term antitumor chemotherapy, thus, the processes of bone reparatation and regeneration occur against this background. The cases of fractures may be due to the development of osteoporosis in cancer and the occurrence of metastatic bone lesions. Bone fractures impair the quality of life of patients, result in the postponement or even discontinuation of further treatment of cancer patients. All this reduces the survival rate of such patients. Therefore, the aim of this study was to establish the effect of antitumor chemotherapeutics on the processes of reparative bone regeneration. The study involved 52 white laboratory rats, which had a perforated defect in the middle third of the femoral shaft. The animals were divided into control and experimental groups. Antitumor chemotherapeutics, which are the most often used in chemotherapy protocols in the treatment of cancer (doxorubicin for the first subgroup, 5-fluorouracil for the second subgroup, methotrexate for the third subgroup) were given to the animals of the experimental group on the second day since modelled injury and every twenty-first day of the experiment. On the 15th, 30th, 45th, and 60th days of the experiment, all animals in the control and experimental groups were check with computed tomography, which determined the optical density in the area of regeneration and the adjacent cortical layer of the maternal bone in Hounsfield units. Conclusions. CT assessment enables to quantify the state of the reparative process in the animals of the control and experimental groups, taking prescribed antitumor chemotherapy. In the animals of the control group, the timing and processes of bone reparative regeneration were not impacted. The CT demonstrated the preserved staging of bone callus formation, satisfactory X-ray morphological parameters (size, thickness of the callus). In the period from 45 to 60 days, according to CT, the complete consolidation of femoral fractures was visually observed. The difference between the parameters of the regenerated area and the maternal bone on the 60th day of the experiment indicated the incomplete process of bone remodelling. Reparative osteogenesis was not accompanied by the development of complications. In the animals of the experimental groups, there was a slowdown in the processes of reparative bone regeneration and an increase in its duration. Indices of callus formation on the background of antitumor chemotherapy were reduced that confirms the low optical density of regenerating area and maternal bone compared to the control group and their slow increase in the defect healing. Most of these changes were manifested during the course of methotrexate therapy.

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