Patients with malignant neoplasms have an increased risk of atrial fibrillation. Prevalence of this pathology among oncological patients is 20–30 %, and it significantly varies depending on tumor type, chemotherapy treatment and initial comorbid status. Atrial fibrillation and malignant neoplasms have similar risk factors. Researchers have identified several possible causes characteristic of these diseases, primarily, systemic inflammation. Some chemotherapies cause abnormalities in ionic channels of atrial cardiomyocytes which leads to changes in the action potential and refractory period, which promote maintenance of atrial fibrillation. The most known groups of chemotherapy drugs associated with atrial fibrillation are alkylating agents (cisplatin, cyclophosphamide), anthracyclines used in sarcoma treatment, as well as anti-HER2 drugs (HER2 – human epidermal growth factor receptor 2), antimetabolites (capecitabine, 5-fluorouracil) and tyrosine kinase inhibitors. However, pathophysiological mechanisms linking together atrial fibrillation and malignant neoplasms require further study.

Introduction. Radiation therapy remains one of the main methods of radical treatment of early-stage skin cancer. Its position in combination and comprehensive treatment has changed significantly as improvements of radiotherapy techniques and introduction of modern technologies led to increased effectiveness and comfort of the method and allowed to achieve better prognostic outcomes.

Aim. To evaluate the role of radiotherapy in treatment of patients with early-stage skin cancer (T1–2N0M0).

Materials and methods. A retrospective and prospective analyses of data from 1049 patients with early-stage skin cancer were performed. In 527 (50.23 %) cases, the tumor was localized mainly on the head and neck: 48 % of patients had nonkeratinizing squamous cell carcinoma of the skin, 7.59 % of patients had keratinizing squamous cell carcinoma, 44.41 % of patients had basal cell carcinoma.

Results. Data from 527 patients (51.04 % man and 48.96 % women) with early-stage skin cancer (T1–2N0M0) who received treatment and are registered at the Republican Oncological Scientific Center of the Ministry of Health and Social Protection of the Tajikistan Republic were analyzed. The disease was more common in patients aged between 60 and 90 years. The main factor in stage determination was tumor size in accordance with the Tumor, Nodus and Metastasis (TNM) classification. In 240 (46.54 %) patients, the size of primary tumor was less than 2 cm in the largest diameter (T1N0M0), in 287 (54.46 %) patients its maximal size was between 2 and 4 cm (T2N0M0). Selection of treatment method was mainly based on morphological characteristics and location of the tumor. In 121 (50.42 %) patients with skin cancer T1N0M0, radiation therapy was performed as monotherapy in a radical program; in 88 (36.37 %) patients in combination with cobalt therapy and surgery; in 23 (9.59%) patients in combination with cobalt therapy, polychemotherapy and surgery; in 8 (3.41%) patients in combination with cobalt therapy and polychemotherapy.

The capabilities of radiation therapy both as monotherapy and in combination with other treatment methods before and after surgical treatment present ample opportunities for clinicians to achieve good outcomes. The use of radiation therapy as monotherapy in a radical program in patients with T1N0M0 stage skin cancer is effective in 96.4 % of cases, in patients with stage T2N0M0 the effectiveness can reach 91.2 %.

Conclusion. Radiation therapy can be successfully used in treatment of early-stage skin cancer along with other methods. Its use both independently and as part of combination and comprehensive therapy allows to achieve reliable treatment outcomes. Adequate selection of radiation therapy option in treatment of early-stage skin cancer is the key to longterm clinical remission and improvement of patients’ quality life.

Introduction. Endoprosthesis of large joints is associated with high risk of venous thromboembolism. Researchers focus on biochemical characteristics of homeostasis, blood clotting in particular, as the main reason for abnormal blood flow. At the same time, biophysical condition of homeostasis, namely decreased blood fluidity, is rarely considered. Study of rheological behavior of blood after primary oncological endoprosthesis of large joints in patients can potentially affect the selection of perioperative thromboprophylaxis and patient rehabilitation approach.

Aim. To study the indicators of the hemorheological status of patients with tumours of long bones in the preand postoperative periods of primary oncological knee replacement.

Materials and methods. The study included 36 patients (26 men and 10 women, mean age 46 years) without cardiovascular diseases and pathology of the veins of the lower limb admitted to the Russian Scientific Center of Roentgen Radiology for oncological endoprosthesis of the knee joint. All patients were prescribed: an antiplatelet agent (acetylsalicylic acid) and an anticoagulant (enoxaparin sodium 40 mg daily). Distal resection of the femur (on average 14 cm) was performed in 28 patients, and proximal resection of the tibia (on average 12 cm) in 8 patients, followed by knee replacement. Before the operation, on the 1st and 6th days after the operation, the hemorheological status and the state of the hemostasis system were evaluated in all patients. To determine the reference values, 24 healthy people were examined, comparable in gender and age. Statistical analysis using Statistica 10.0.

Results. During the preoperative examination, integral assessment showed the differences in the severity of hemorheological disorders between patients, and two groups were identified: Group 1 – 21 (61 %) patients whose hemorheological disorders were classified as severity degree I, and Group 2 – 14 (39 %) patients with severity degree II d. On day 1 after the surgery, both patient groups showed negative dynamics: hemorheological disorders in group 1 worsened from grade I to II d., and in group 2 to III d. (critical) (p <0.05). On day 6, the parameters did not change significantly in all patients. Similar dynamic changes were observed in the haemostasis system.

Conclusion. Activation of the blood coagulation system and deterioration of hemorheology occurred after surgery during administration of anticoagulant and antiplatelet therapy. None of the patients had venous thromboembolic complications, however the risk of their development remained high. A differential model describing hemorheological status can be useful for selection of thromboprophylaxis and rehabilitation methods which include physical factors that improve the hemorheological profile: low-frequency magnetic and/or laser therapy in patients.

Introduction. Canine osteosarcoma is a most common bone tumor in dogs, usually involving long tubular bones lesion. Limb-sparing treatment method allows to save extremity functionality and sufficiently improve quality of life in comparison with amputation.

Aim. To analyze the survival rates and local results after limb-sparing treatment of canine osteosarcoma using bio-implantation – de-immunized allogenic bone populated with recipient stromal mesenchymal cell preparation.

Materials and methods. Group of 25 dogs underwent a combined treatment including cisplatinum chemotherapy (60–70 mg/m² intravenously infusion at 14–21 day intervals, up to 4 cycles) and wide segmental resection of the affected bone with a bioimplant defect replacement. Overall survival, progression-free survival and local recurrence frequency in the group were analyzed.

Results. Overall survival median was 321 day, and progression-free median was 222 days. 4 (16,6 %) cases of local relapse were recorded, 2 of which were confirmed by radiography and histological examination, and 2 other by radiography only.

Conclusion. Efficiency of the canine appendicular osteosarcoma combined limb-sparing treatment is comparable with amputation practice results (according to scientific literature) while foregoing method is preferable due to higher life quality of patients.

Introduction. The distal tibia and fibula are rare sites of involvement by primary and metastatic tumors. For a long time, amputation remained the standard surgical intervention for this location. Oncological ankle replacement is associated with a number of difficulties, including a lack of soft tissue necessary to cover the implant, close proximity of anatomical structures, a high probability of vascular and infectious complications, and difficulties in restoring the biomechanics of the lost joint. Currently, due to the small number of analyzed groups and short-term observations, there is no generalized data on primary and revision oncological ankle replacement, and there is no developed approach to treatment and prevention of complications.

Aim. To generalize the analysis of long-term results, the structure of complications, and functional results in a group of patients after primary and revision oncological ankle replacement in a statistically significant group of patients.

Materials and methods. The study included 40 patients with benign bone tumors, primary localized sarcomas of bone and soft tissue, and metastatic lesions, which, since 2008, until 2023 56 primary and revision endoprosthetics of postresection defect of the distal tibia were performed. Over a period of 15 years, the study group included 40 (71.4 %) surgeries in the scope of primary endoprosthetics and 16 (28.6 %) surgeries in the scope of revision oncological endoprosthetics of the ankle joint.

Results. Over a 15-year follow-up period, the overall incidence of complications, structured according to the International Society of limb Salvage (ISOLS) 2013 classification, after primary and revision arthroplasty was 50 %. The average time until detection of oncological and non-oncological complications was 16.1 months. The leading complication after endoprosthetics was aseptic instability (Type II; 21.4 %) and tumor recurrence (Type V) – 20 %. The average functional outcome after primary and revision ankle replacement was assessed using the MSTS scale and was 72 % after 6 months and ranged from 43 to 97 %. After 12 months, this figure was 78 % and ranged from 49 to 97 %.

Conclusion. An objective assessment and increase in the statistical reliability of the results of oncological ankle replacement requires a larger number of surgeries, a longer observation period and joint consolidation of data from various clinics. Development of indications for such reconstructive operations, careful selection of patients taking into account the effect of conservative treatment allows to reduce the total number of complications, the number of local relapses and achieve a good functional result.

Leiomyosarcoma of the diaphragm is an extremely rare disease. No more than 20 cases have been described so far. All patients needed reconstruction of the dome of the diaphragm, including with the use of implants. The article presents a clinical case of treatment of a 40-year-old woman with giant leiomyosarcoma of the left diaphragmic cupola.The extirpation of the tumor as a single block with the diaphragm and the pericardial wall was performed, followed by the restoration of the abdominal obstruction with nickel-titanium metal knitwear.

Introduction. Primary spinal osteosarcoma and rare metastatic heart lesion are considered significant factors for poor prognosis. The available work indicates that combined treatment, including the radical surgery of heart solitary metastatic lesion, probably provides the best outcome.

Case report. Man, 27-year-old, with Th8 spinal osteosarcoma and solitary left atrial metastasis. From October 2019 to February 2020 5 cycles of chemotherapy (high doses of platinum and doxorubicin) were carried out with positive effect. Next steps were surgery: March 2020 – spondylectomy of the Th8 vertebra with combined stabilization; September 2020 – subtotal resection with plasty of the right atrium, tricuspid valve and prosthesis of the right coronary artery. Between the first and second surgery, 4 more same chemotherapy cycles were carried out. Currently, 24 months after completion of treatment, there are no signs of the disease.

Conclusion. The article presents a unique case of treatment of primary osteosarcoma and metastatic lesion of rare location. Multidisciplinary approach and combination treatment in specialized centers increase the probability of favorable outcome in such cases.