Yanchevskyi O. Clinical-morphological and molecular-genetic features of small cell lung cancer

The thesis is devoted to the improvement of diagnosis and morphological criteria for prognosis of small cell lung cancer (SCLC) based on the study of clinical-morphological and molecular-biological characteristics of primary tumors with different clinical behavior and prognosis. As a result of the research, it was established that SCLS accounts for 28.8% of all lung cancers in patients who died in multidisciplinary hospitals. It has been proven that TTF1 and p40 markers can be considered the most valuable for the differential diagnosis of SCLC with squamous cell carcinoma. Ki-67 can be used for differential diagnosis of SCLS with carcinoids, but not for differential diagnosis with other malignant neoplasms. CD56 makes it possible to determine the neuroendocrine nature of tumors. A combination of immunohistochemical markers: TTF-1/CD56 (2-4 points)/p16/CD117 is proposed, which (with sensitivity – 80.0% and specificity – 86.67%; p=0.0003) will allow differential diagnosis between SCLC and other neoplasms with similar morphology; immunohistochemical features of the medical pathomorphosis of SCLC were determined. An optimal panel of immunohistochemical markers for the diagnosis of SCLC, determination of their biological behavior and prognosis of the disease is proposed.. The prognostic immunohistochemical criteria of SCLC have been identified. Unfavorable prognosis criteria include: appearance of vimentin expression in cancer cells, increased level of N-cadherin expression, presence of epithelial-mesenchymal transformation (EMT) and EMT stages 3-5. The classification of EMT SCLC is proposed taking into account the expression of phenotype markers of epithelial and mesenchymal tissues. It was demonstrated that EMT was observed in 69.3% of SCLC and its presence was associated with widespread forms of SCLC. The obtained data made it possible to form prognostic criteria for a favorable course of the disease and a fatal outcome in patients with SCLC.