Purpose: to determine the real state of cancer care in Russia for the identifcation of patients with postmortem diagnosis of cancer using the population-based cancer registry. Material and Methods. Data from the offcial reports of the cancer service (f. No. 7) and the database of the population-based cancer registry of the Northwestern Federal District of the Russian Federation with a volume of more than 1,350,000 cases of cancer were presented. Standard methods of cancer statistics were used. Results. The problem of the quality of registration of primary patients with cancer includes three main components: active cancer detection, including screening programs and medical survey; providing citizens with optimal conditions for free access to medical institutions, including cancer centers; improving the pathoanatomical service to detect cancer in deceased patients. The proportion of patients registered postmortemly, according to offcial data, may be several times less than the real value. At the same time, it should be noted that for 2 periods (1997–1999 and 2017–2019), according to the database of the Northwestern Federal District of the Russian Federation, the proportion of postmortemly registered patients decreased from 15.72 to 8.16 %, and in St. Petersburg from 24.46 to 9.76 %. During the period from 2017 to 2019, 2973 patients with bronchial and lung cancer (C34) – 15.17 %, 1708 patients with colon cancer – 10.32 %, 1640 patients with stomach cancer – 12.17 %, about 20 % of patients with pancreatic cancer and 29.43 % of patients with liver cancer were unaccounted for in the Northwestern Federal District of the Russian Federation. Conclusion. Thus, for the frst time in Russia, our study made it possible to identify the real state of cancer care for patients with post-mortem diagnosis of cancer, to determine the magnitude of the discrepancy between state reporting data and database of population-based cancer registry, to note the improvement in one-year and fve-year observed survivals. In recent years, the one-year mortality rate, subject to posthumously registered patients, loses 5.6 years, fve-year – 4.4 years. It is important to note that since 2000, due to improved registration of patients with a frst-time diagnosis of malignant tumors, the one-year and fve-year survivals of patients with posthumously registered increased by 18.5 % and 20.7 %, respectively.

Purpose. To evaluate prostate specifc antigen density (PSAD) as a predictor of overall (OS) and cancerspecifc survival (CSS) in patients with prostate cancer (PC) who have undergone combined hormonal-radiation therapy.

Material and Methods. In order to assess the prognostic signifcance of PSAD we retrospectively analyzed outcomes of 714 PCa patients who received combined hormonal-radiation therapy at the A.M. Granov Russian Scientifc Center of Radiology and Surgical Technologies, Ministry of Healthcare of Russia, between January 1996 and December 2016. Since the prognosis and management differ according to the extent of tumor involvement, patients were categorized into localized (n=272), locally advanced (n=231) and metastatic (n=211) PC groups. We equentially applied ROC-analysis, Kaplan-Meier product limit estimator and Cox proportional hazards model to assess the prognostic relevance and establish threshold values of PSAD that had a signifcant impact on survival rates.

Results. In the localized PC group, PSAD threshold values of 0.34 ng/mL/cc and 0.36 ng/mL/cc were associated with a decrease in OS and CSS, respectively. Patients with “low” PSAD had signifcantly better OS and CSS survival rates in both uni- and multivariate analyses. In locally advanced PC group, PSAD threshold values were 0.28 ng/mL/cc and 0.63 ng/mL/cc for OS and CSS, respectively. However, exceeding the specifed values, in the locally advanced PC group, was not accompanied by a statistically signifcant decrease in survival rates. Finally, in the metastatic PC group, established PSAD threshold values were 2.25 ng/mL/cc and 2.30 ng/mL/ccfor OS and CSS, respectively. According to the results of univariate analysis, patients with “low” PSA tend to demonstrate statistically signifcant better OS and CSS rates. The results of multivariate analysis, however, failed to prove PSAD as an independent prognostic factor within the metastatic PC cohort. Conclusion. PSA density is a reliable tool for assessing survival rates in patients with localized PC who have undergone combined hormonal-radiation therapy.

Venous thromboembolism (VTE) is often diagnosed in patients with pancreatic cancer, resulting in increased morbidity and mortality. Objective: to study the relationship between clinical characteristics and hemostatic disorders in patients with pancreatic cancer and determine their role in predicting VTE. Material and Methods. The study included 246 patients with pancreatic cancer. Pancreatic ductal adenocarcinoma was diagnosed in 91.9 % of patients. In most patients (68.3 %), the tumor was localized in the head of the pancreas; 45.9 % of patients had stage IV disease at diagnosis (T1–4N0–2M1); 31.7 % of patients manifested jaundice at diagnosis. A small proportion of patients (17.5 %) received chemotherapy, and 28 % of patients underwent surgery. Within the 12-month follow-up period, the frequency of VTE was 15.4 %. Clinical characteristics and hemostasis parameters were retrospectively compared in patients with VTE and without VTE diagnosed during the follow-up period. Results. The risk of developing VTE in cancer patients was higher with a larger tumor size and the presence of distant metastases. The initial high level of D-dimers increased the risk of VTE during the frst 12 months of diagnosis. In a multivariate analysis, the elevated level of D-dimers was a signifcant risk factor for VTE. Conclusions. The tumor size, advanced tumor stage (stage IV), and elevated levels of D-dimer in patients with pancreatic cancer are of prognostic signifcance for VTE. The study of hemostasis parameters (D-dimer) can help identify patients at risk of developing VTE, who are advised to take anticoagulant therapy with low hemorrhagic risk.

Introduction. The incidence and mortality of malignant melanoma have increased steadily over the last decades; therefore, the development of novel diagnostic markers for malignant melanoma is of great importance. The purpose of the study was to assess whether the development of melanoma before any treatment is accompanied by the body changes and, in particular, DNA damage in the mononuclear cells of the peripheral blood of patients. Material and Methods. In 93 patients (26 men and 67 women) admitted to the N.N. Petrov National Medical Research Center of Oncology for surgical treatment of stage T1c-2a-b-3a-b4a-bN0-1 cutaneous malignant melanoma, and in 118 healthy people as a comparison group, the level of damage to DNA in peripheral blood mononuclear cells was studied using the “comet” method. All patients were divided into two groups: group 1 included 45 patients (13 men and 32 women) who were examined before a decision on treatment was made and group 2 consisted of 48 patients (13 men and 35 women) who previously underwent excision biopsy for melanoma. Results. The level of DNA damage in peripheral blood mononuclear cells, assessed by the comet assay, was found to be signifcantly higher in patients with melanoma than in the comparison group. Moreover, the increase in the level of DNA damage was similar both in patients with a primary tumor before starting any treatment and in those who previously underwent excision biopsy for melanoma. The relationship between the level of DNA damage in peripheral blood mononuclear cells and the morphological characteristics of the tumor cells was revealed. The Spearman correlation analysis showed that all parameters that determined DNA damage positively correlated with the thickness of melanoma according to the Breslow’s depth, and the percentage of DNA in the comet and the comet tail moment correlated with the stage of the disease. Conclusion. The development of cutaneous melanoma is accompanied by an increase in the level of DNA damage in peripheral blood mononuclear cells. The level of DNA damage in peripheral blood mononuclear cells refects the changes that occur in the patient’s body under the infuence of the tumor process, which may allow using this indicator as an additional criterion for the diagnosis and aggressiveness of melanoma.

Purpose. To study suppressor and/or cytotoxic activity of the nuclear erythroid cells (NEC) against tumor cells of various origins. Material and Methods. C57Bl/6 mice and P815, L1210, B16 and L929 tumor cells were used. “Phenylhydrazine” NECs were obtained from mice with induced hemolytic anemia. “Erythropoietin” NECs were isolated from the “phenylhydrazine spleen” and further cultured in the presence of erythropoietin. Another source of NEC was neonatal mouse spleen, human and mouse fetal liver cells, and mouse bone marrow cells cultured with erythropoietin. The cytostatic effect of NEC or their supernatants was recorded by reducing proliferation of P815, L1210, B16, LLC, L929 lines. Results. The presence of pronounced direct antitumor activity was found in both NEC and their culturing products in relation to cells of various tumor lines. The suppressor effect was not specifc. Conclusion. We know about the signifcant numerical predominance of NEC during the embryo development over all other hematopoietic cells and their high suppressive potential. Therefore, it can be assumed that erythroblasts are involved in process of creating antitumor protection of a fetus during this period of life.

Objective: screening of previously selected DDIT4 inhibitors by their ability to suppress basal and glucocorticoid-induced expression of this gene in breast cancer (BC) cells, as well as evaluation of antiproliferative and cytotoxic effects of the studied drug combinations the antiproliferative and proapoptotic effects of studied drug combinations. Material and Methods. Breast cancer cells of the luminal, HER2- positive and triple negative subtypes were used. The effects of drugs (rapamycin, wortmannin, LY-294002, apigenin, resveratrol, curcumin, CGP-60474, and emetine) on the basal and glucocorticoid-induced levels of expression of the DDIT4 gene and its protein product were evaluated by qPCR and Western blotting assays. Results. Emetine, rapamycin, wortmannin, LY-294002 and CGP-60474 demonstrated DDIT4-inhibition activity. Glucocorticoid dexamethasone showed cytotoxic effects and antiproliferative activity in combination with emetine, CGP-60474 (C protein kinase inhibitor), resveratrol and curcumin. Conclusion. Novel inhibitors of DDIT4 in breast cancer model cells in vitro were found. Emetine and CGP-60474 are the most promising drugs for further research.

Objective. To evaluate anti-tumor, toxic effect of miR-204-5p mimic applicaton on melanoma B-16-bearing mice followed by miR-204-5p target gene expression estimation in melanoma tumor and distant organs. Material and Methods. C57Bl/6 melanoma B-16-bearing mice were used. The animals of the experimental group were intraperitoneally injected with a 5 nM miR-204-5p miRNA simulator (mimic) on the 8th, 10th, and 12th days after melanoma B-16 cell transplantation. Based on the results of bioinformatic analysis, miR-204-5p target genes BCL2 and SIRT1 expression levels were determined by quantitative real-time PCR. The toxic effect of miR-204-5p mimic was estimated by the evaluation of body weight, mass of the internal organs, and motor activity. Results. On the 13-14th days of the experiment, the motor activity of animals in the control groups decreased signifcantly compared to the group of animals treated by miR-204-5p. Target gene BCL2 showed increased expression in the lungs and kidneys and SIRT1 levels were increased in the lungs of miR-204-5p mimic treated animals (p˂0.05). Tumor mass tended to decrease in the animals treated by miR-204-5p mimic. Conclusion. Modulation of the level of miR-204-5p microRNA led to changes in the expression of SIRT1 and BCL2 in the lungs of animals, and changes in the expression of BCL2in the kidneys. MiR-204-5p mimic application did not have toxic effect on animals treated. Further studies are necessary to clarify miR-204-5p implication in melanoma cell proliferation regulation as well as it’s biodistibution in the tumor tissue.

Relevance. The global trend of rapid increase in resistance to antifungal drugs due to multiple factors, dictates the need for continuous monitoring of taxonomic structure and susceptibility of nosocomial pathogens, causing invasive fungal infections, for permanent correction of the optimal prevention and treatment strategies.

Purpose: to determine antifungal susceptibility of the main yeast pathogens in candidemia in cancer patients, as well as to determine resistance genes and pathogenic factor genes.

Material and Methods. Eighty-two strains of Candida spp. isolated from blood of cancer patients from 2015 to 2021 were analyzed. Minimum inhibitory concentrations of fuconazole, voriconazole, posaconazole, anidulafungin and micafungin were determined by a gradient method (E-test, BioMerieux, France). The EUCAST and CLSI criteria were used for MIC value assessment. The genes, associated with pathogenicity factors, and resistance to antifungal drugs were identifed.

Results. Our study results based on EUCAST 2020, v.10.0 criteria showed that triazoles, especially fuconazole, were the least effective drugs in empirical therapy for invasive candidiasis (including candidemia). Resistance of Candida spp. fuconazole was superior to that of voriconazole (47.2 % vs 23.2 %, respectively, p<0.01) and posaconazole (47.2 % vs 30.4 %, respectively, p><0.05). The highest in vitro activity was observed in echinocandins, and anidulafungin was 2 times more active than micafungin (4.1 % of resistant strains vs 11.4 %, respectively), with no statistically signifcant difference (p>0.05). The ERG11 and FKS1 genes associated with resistance to antifungal drugs were detected in 28.6 % of Candida spp. strains. The ERG11 gene was detected in 8.6 % of cases, exclusively in Candida albicans strains. The FKS1 gene was identifed in 20.0 % of strains (85.7 % of them were C. parapsilosis, 7.1 % each were C. tropicalis and C. glabrata). Pathogenic factor genes were identifed in 78.6 % of C. albicans and in 79.1 % of C. parapsilosis strains.

Conclusion. Molecular genetic methods for the detection of Candida spp strains carrying resistance genes to antifungal drugs, and the determination of pathogenicity factors are promising trends in searching for biomarkers. They facilitate interpretation of results of microbiological study to assess the ability of Candida spp. strains to develop invasive mycoses.

Background. Recent studies have shown that a combination of surgery with chemotherapy and radiotherapy can signifcantly improve survival in patients with primary and metastatic bone tumors. Reconstruction of bone defects after resection of long bones is critical for successful functional limb salvage. The choice of the reconstruction technique depends on the tumor location, tumor extension, presence of pathological fracture, and somatic status of the patient. Reconstruction of bone defects in cases with diaphyseal tumor location can pose a surgical challenge. For the reconstruction of diaphyseal bone defects, endoprostheses, alloimplants, and autologous bone grafts are used. To achieve stability of the affected segment of the limb, various options for osteosynthesis are used. Modern technological achievements provide the emergence of materials with characteristics close to those of human bone tissue, however, without the disadvantages inherent in allo- and autologous implants. The purpose of the study was to improve surgical treatment outcomes in patients with long tubular bone tumors. Material and Methods. For the reconstruction of postoperative long bone defects, we used carbon nanostructured implants (СNI) in combination with intramedullary osteosynthesis with a blocked pin. A total of 25 patients underwent surgery (including 9 patients with a pathological fracture), 24 of them had metastases. Results. There were no intraoperative and postoperative complications. All patients had a signifcant decrease in pain 1 month after surgery. At 3 months after surgery, functional outcomes were satisfactory. None of the patients had a local recurrence, instability of the operated limb segment, or a reaction of rejection of a carbon nanostructured implant. Conclusion. Reconstruction of postoperative defects with carbon nanostructured implants after resection of long tubular bones for metastatic cancer provides good functional results and satisfactory local control.

The purpose of the study was to present current data on the role of lifestyle and heredity factors in the etiology of pancreatic cancer (PC). Material and Methods. A systemic literature search was conducted using Medline and Elibrary databases. Results. Pancreatic cancer is the 9th leading cause of cancer-related deaths worldwide. PC has an extremely poor prognosis. The 5-year survival rate of patients with PC does not exceed 9 %. The highest incidence and mortality rates from PC are found in Eastern Europe, including Russia. The incidence of PC in 2019 was 9.3 per 100,000 males and 5.7 per 100,000 females. In Russia, PC incidence and mortality rates in both males and females show a steady increase. Risk factors associated with PC include smoking, heavy alcohol drinking, overweight and obesity, diabetes and chronic pancreatitis. The microbiome of the oral cavity and colon infuence the risk of PС. Approximately 10 % of PC is estimated to have familial inheritance. The risk of PC in patients with inherited syndromes ranges from 2 (hereditary breast and ovarian cancer syndrome) to 132 (Peutz-Jeghers syndrome). Regions of the genome containing variants of single nucleotide polymorphism (SNPs), which are more common in patients with PC than in healthy people, were identifed. The most common somatic mutations include mutations in the driver genes of prostate cancer, which include the KRAS oncogene and tumor suppressor genes TP53, CDKN2A, and SMAD4.The less common mutations of genes include AIB1/NCOA, ERBB2/HER2/EGFR2, AKT2, BRAF, CCND1, RB1, etc. They are identifed as “passenger” mutations although the combined effect of polymorphism of these genes can be signifcant and comparable to the infuence of the driver gene. Conclusion. A signifcant disadvantage of our understanding of the process of carcinogenesis is the lack of information about carcinogenic factors that cause specifc mutations, i.e. the formation of mutational signatures. To solve this problem, in 2017, the international scientifc project GRAND CHALLENGE “Mutograph” was launched. The scientists of the Department of Cancer Epidemiology of N. N. Blokhin National Medical Research Center of Oncology are members of the international team working on this project.

Purpose: to summarize available data on the diagnostic value of various circulating biomarkers for the detection of glioblastoma recurrence.

Material and Methods. A literature search was conducted using PubMED ExoCarta and SILVA databases.

Results. Glioblastoma multiforme (GBM) is the most common glioma in adults with an unfavorable prognosis. Treatment of tumor recurrence can improve the survival of patients. Neuroimaging is the standard method of diagnosing brain tumor recurrence. However, a neuroimaging method to clearly distinguish between pseudo progression and tumor progression has not been found to date. Current molecular tumor profling relies heavily on tissue resection or biopsy. Tissue profling has several disadvantages in the central nervous system’s tumors, including the challenge associated with invasive biopsy, the heterogeneous nature of many malignancies where a small biopsy can under represent the mutational profle. Liquid biopsy is a promising method in diagnosing malignant tumors. Blood collection is a simple, minimally invasive procedure, but cerebrospinal fuid allows tumor markers to be detected more confdently. However, collection of cerebrospinal fuid is a complex and invasive procedure that can be accompanied by serious complications.

Conclusion. Biological fuid markers such as circulating tumor cells, extracellular vesicles, cell-free DNA and cell-free RNA allow for the detection of GMB, determination of molecular genetic features of cancer during response to therapy, and early detection of GBM recurrence.

Purpose of the study: to identify general patterns in the presence of detectable amounts of circulating tumor cells (CTCs) negatively correlated with the overall survival of patients and their ability to form metastases in distant tissues and organs, as well as to summarize the biological properties and interactions of CTCs with other cell types during intravasation, circulation, extravasation, and colonization, which involve changes in CTC phenotypes that are regulated by many signaling molecules, including cytokines and chemokines. Material and Methods. We analyzed publications available from PubMed (https://pubmed.ncbi.nlm.nih.gov), Scopus (https://www.scopus.com/), Web of Science (https://apps.webofknowledge. com/WOS_GeneralSearch), Cancer Tomorrow (https://gco.iarc.fr/tomorrow/en), and Global cancer observatory (https://gco.iarc.fr) databases between 2000–2021 using the keywords “circulating tumor cells”, “biomarker”, “metastasis” and others. Results. Monitoring of blood levels of CTCs can have exceptional prognostic and monitoring implications. Liquid biopsy to detect CTCs and their progeny can be used to diagnose cancer in the general population, as well as to predict biomarkers in cancer patients. The improvement in the CTC detection technology and clinical trials in large prospective studies will increase the clinical usefulness of these marker cells. Understanding of their biology and interactions with other cell types, especially with the immune cells, and the development of CTC immunotherapy also holds great promise in cancer therapy. Conclusion. Currently, CTCs are not routinely used in clinical practice, but research in this area continues to accumulate the data on the clinical validity of CTC detection. This is due to the feasibility of monitoring the patient’s condition using liquid biopsy for the CTC detection. We present an overview of the clinical value of CTCs as a biomarker, as well as key studies examining the clinical usefulness of CTCs.

The purpose of the study was to summarize available data on genetic counseling for people with hereditary diffuse gastric cancer (HDGC) syndrome, treatment strategies for family members with HDGC, prophylactic gastrectomy (PGE), and surveillance of CDH1 and CTNNA1 mutation carriers. Material and methods. A literature search was conducted using Web of Science, Scopus, MedLine, Cochrane Library, and RSCI databases. Results. HDGC syndrome is an inherited genetic syndrome that leads to the increased risk for both diffuse gastric cancer (DGC) and lobular breast cancer (LBC). About 1 to 3% of all gastric cancer cases are HDGCs. A high frequency of CDH1 gene mutation was frst identifed by P. Guilford et al. in 1998 in 3 Maori families from New Zealand. The cumulative risk for HDGC in CDH1 mutation carriers is 42 to 70% for men and 33-56% for women at the age of 80 years. Due to the rarity of the disease, the main publications dealing with this problem are clinical case descriptions. Conclusion. Multicenter clinical trials are required to improve screening and management of HDGC syndrome.

The purpose of the study was to generalize information regarding the molecular and biological mechanisms involved in the resistance to endocrine therapy with aromatase inhibitors in patients with luminal breast cancer. Material and Methods. The literature search was conducted using Medline, Cochrane Library, Elibrary and PubMed databases. Results. The review highlights the results of international studies on molecular and biological characteristics of breast tumors and their relationship with the effectiveness of hormone therapy. Particular attention was paid to the description of modern studies on ROR1 and BMI-1 proteins and their contribution to the development of tumor resistance to treatment. Conclusion. The analysis of the world literature confrms the relevance of studying the molecular and genetic characteristics of tumor tissue in patients with luminal breast cancer. The data obtained were compared to the clinical course and response to hormone therapy in order to standardize them for implementation in everyday practice as the “gold standard of diagnosis”.

Relevance. Lung cancer (LC) is the leading cause of cancer-related death worldwide including Russia. Surgery remains the standard of care for early non-small cell lung cancer (NSCLC). However, as the disease progresses, the risk of metastasis increases, and the effectiveness of surgical intervention decreases. The treatment strategy for patients presenting with a single NSCLC has long been developed. However, for patients with two or more tumors, especially in both lungs, the correct choice is determined by many additional factors. Currently, the view on the surgical treatment for synchronous multiple primary NSCLC has changed dramatically. However, patients with locally advanced synchronous NSCLC often receive conservative treatment, and for those who do undergo surgery, the prognostic factors are unclear. The disease prognosis in patients after surgical treatment for bilateral synchronous multiple primary NSCLC has now been proven to be favorable. Pneumonectomy is believed to have no any negative effect on survival; however, several authors reported on a 1.5-2-fold increase in postoperative mortality in a series of surgeries for synchronous NSCLC. Case description. We herein report a case in which extended bronchoplastic upper lobectomy was successfully applied in the treatment of a patient with bilateral synchronous NSCLC. Our experience demonstrates that the sequential application of modern therapeutic modalities results in satisfactory long-term outcomes in the treatment of locally advanced LC.Conclusion. Due to its uniqueness, this clinical case will be useful for developing treatment strategy for synchronous locally advanced NSCLC as well as for improving the quality of life of patients and increasing their survival.

Background. Tracheal cancer accounts 2 % of all upper respiratory tract cancers, with the incidence of 0.1 cases per 100,000 people per year. Primary tracheal MALT-lymphoma is extremely rare, and therefore there is no clearly established approach to the treatment of this disease. There are several effective positions regarding the choice of therapy. This article discusses the feasibility of endoscopic surgical treatment of primary tracheal lymphoma. The review of the literature presents current data on the epidemiology, etiopathogenesis, clinical features and treatment strategy for this disease.

Description of the clinical case. A 72-year-old patient was admitted to the Thoracic Surgical Department of the P.A. Hertzen Cancer Research Center with complaints of shortness of breath with moderate physical exertion and dry cough. The examination revealed a tumor in the upper third of the trachea showing an exophytic growth, and grade I–III tracheal stenosis. To restore the lumen of the trachea and prevent complications, the endoscopic resection of the exophytic part of the tumor was performed. Histological and immunohistochemical studies revealed MALT-lymphoma of the trachea. Taking into consideration the indolent form of lymphoma, small size of the tumor, patient’s age and comorbidity, there were no indications for systemic anticancer therapy. The patient was recommended to be followed up. The patient is alive with no evidence of disease recurrence.

Conclusion. This case report demonstrates the feasibility of performing organ-preserving endoscopic surgery in the patient with primary tracheal MALT-lymphoma. Taking into consideration the exophytic form of the tumor growth, endoscopic surgery made it possible to avoid unnecessary open tracheal resection, thus signifcantly improving the quality of life of the patient.

Background. Neuroendocrine tumors (NETs) of the small bowel are rare and slow-growing tumors arising from intraepithelial endocrine cells that synthesize serotonin. Diagnosis of these tumors poses a signifcant challenge because they are often not diagnosed until an advanced stage, since the tumor may be asymptomatic or accompanied by non-specifc gastrointestinal complaints. Approximately 40 % of patients develop carcinoid syndrome due to hormonal activity of NETs. Surgery is the mainstay treatment of locoregional small bowel NETs. The fve-year survival rate of patients is about 85 %, with a median rate of 9.3 years.

Case description. The female patient complained of facial redness and, to a lesser extent, redness of the skin of the trunk, accompanied by a feeling of heat, severe headache, lacrimation, and general feeling of weakness. The patient unsuccessfully received symptomatic treatment prescribed by various specialists (gynecologist, therapist, psychiatrist, endocrinologist, etc.) for 14 years. Based on the comprehensive examination, NET of the small bowel was diagnosed. The patient underwent radical surgery (pT2N1M0, stage IIIB, G2), but taking into account the unfavorable prognostic factors (metastases in the mesenteric lymph node, presence of carcinoid syndrome, elevated biochemical markers, Ki67 level = 6 %, presence of somatostatin receptors of 2 and 5 types in 60 % of tumor cells), the patient was further treated with somatostatin analogues.

Conclusion. When small bowel NETs are suspected, especially with the evidence of carcinoid syndrome, every effort should be made to confrm the diagnosis using a combination of anatomical and functional tumor imaging with biochemical markers.

Background. Coronavirus disease 2019 (COVID-19) is a pandemic of the new millennium. COVID-19 can cause both pulmonary and systemic infammation, and can rapidly progress to multiple organ failure. Data on the relationship between COVID-19 and the thyroid gland have been available since March 2020. The thyroid gland and viral infection as well as associated infammatory-immune reactions participate in a complex interaction. The most common autoimmune disease is chronic autoimmune thyroiditis (chronic lymphocytic thyroiditis, Hashimoto thyroiditis). The majority of medullary thyroid cancers present as a thyroid nodule. Cervical lymph nodes and distant metastases are often detected at the time of diagnosis. The development of autoantibodies may be part of a more complex protective antitumor mechanism, the purpose of which is to eliminate the precursors of future tumor cells.

The purpose of the study was to describe a clinical case of diagnosing medullary thyroid cancer in the patient who had COVID-19.

Case description. We present the case of a 43-year-old woman who had coronavirus pneumonia (COVID-19), which was accompanied by an increase in serum procalcitonin (PC) level, which required additional examination. Since 2020, she had been observed for autoimmune thyroiditis, which was manifested by a thyroid nodular of a small size. After discharge from the COVID hospital, an ultrasound examination of the thyroid gland revealed an increase in the left lobe thyroid nodule up to 15 mm. The level of calcitonin was 681 pg/ml. Fine needle aspiration (FNA) biopsy of the thyroid gland showed suspicion for medullary thyroid cancer. Thyroidectomy with central lymph node dissection (level VI) was performed. A planned histological examination of the surgical specimen confrmed medullary thyroid cancer.

Conclusion. In the present clinical case, medullary thyroid cancer was detected in the patient who had COVID-19 with elevated PC level, which was the basis for a diagnostic search.