e21049 Background: Local and international recommendations for anticancer treatment are formed and changed based on the results of clinical trials. A feature of most clinical trials is the strict criteria used to select “safe” patients without severe comorbidities. In real world practice, significant portion of patients do not meet all of these criteria (32%) [ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7586241/ ], which raises a significant question about the consistency of treatment results demonstrated in studies with data obtained in routine clinical practice (RCP). The purpose of this work was to compare the results of treatment of patients with unrespectable NSCLC receiving first-line drug therapy in RCP and in the framework of international clinical trials using the method of pseudo-randomization (propency score analysis). Methods: The current analysis included 344 patients with inoperable NSCLC who received first-line drug therapy as part of RCP and 90 patients included in various non-TKI clinical trials irrespectively of IO use 2018-2019.Firstly, a direct comparison of performance indicators was done (progression-free survival) using the Kaplan-Meier method for all patients included in the study.At the second stage, in order to eliminate the influence of the imbalance of prognostic factors, a regression analysis was carried out. To form balanced cohorts, we used the propensity score matching analysis.The propensity to progression was assessed using logistic regression analysis in each individual patient, taking into account the basic clinical characteristics: age, gender, ECOG, histological form, regional lymph nodes, presence of distant metastases (mts), stage of the disease, mts of the lung parenchyma, liver mts, pleural mts, bone lesions, adrenal mts, mts lesions of distant lymph nodes, mts lesions of other areas, mts lesions of the brain, number of metastasis zones, components of the first-line therapy regimen. Patients of both arms treatment were matched in a 1:1 ratio based on their progression propensity score in increments of 0.15.After matching two homogeneous groups of patients were formed: 83 in the RCP group and 84 in the clinical trial therapy group. Results: In a direct comparison of the results of the treatment, progression-free survival in the group of patient who underwent treatment in clinical trials was significantly higher than within the RCP (6.4 months 95% CI 5.9–6.9 vs. 13.3 months 95% CI 8.1–18.5; log rank p < 0.000).propensity score matching analysis showed a significantly longer time to progression in the clinical trials group of 13.3 months, 95% CI 8.3-18.3 versus 6.3 months. 95% CI 4.8-7.7; log rank p < 0.000. Conclusions: Results obtained in clinical trial are substantially better than seen in RCP, this should be taken into consideration when extrapolating new research findings.