Role of PD-L1 assessment in the aspect of molecular-genetic classification of colorectal cancer. Current state of the problem

The purpose of the study was to analyze and summarize data regarding a significance of PD-L1 expression in various molecular subtypes of colorectal cancer. Material and Methods. A systemic literature search was conducted in the electronic databases Medline, Cochrane Library, Elibrary, PubMed. Of identified and reviewed 201 full-text articles, we included data from 47 studies. Results. The literature review described the features of the molecular genetic classification of colorectal cancer and revealed the key characteristics of each of the molecular subtypes of this disease. Much attention was paid to the molecular mechanisms of anti-PD-1/ PD-L1 therapy. The main problems associated with the standardization of methods for pathomorphological assessment of the expression of this marker and the difficulties of its interpretation in colorectal carcinomas were outlined. Conclusion. Analysis of the literature revealed problems associated with the assessment of PD-L1 expression in colorectal cancer, in particular, with the lack of generally accepted methods for interpreting research results and standardizing methods for pathomorphological diagnosis of malignant tumors of this localization. Further studies are needed for introducing the molecular genetic classification of colorectal carcinomas into a wide clinical practice and personalizing the approach to therapy of this disease.