[Patterns of CAF expression in tumors of the genitourinary system]

Cancer-associated fibroblasts (CAF), as the most important component of the tumor microenvironment, have been the subject of targeted study in recent years. There is increasing evidence of CAF heterogeneity and their different roles in tumor progression. However, there is no single marker identifying CAF, and there is also no understanding of the similarity of CAF markers in various tumors of the genitourinary system.

To evaluate the response of CAF markers - FAP and PDGFR_α+β in bladder cancer and prostate cancer.

An immunohistochemical study with antibodies to FAP and PDGFRα+β was conducted on material from 34 patients with prostate cancer and 44 patients with bladder cancer in order to identify statistical relationships with stage, morphological characteristics and survival, as well as to understand the applicability of the same markers for cancer of different localizations.

An increased FAP reaction was shown in prostate cancer with metastases (p=0.0239), a significantly higher number of recurrences in the group with a high PDGFR_a+β (3+) reaction (p=0.0018); the presence of FAP reaction only in invasive bladder cancers (p=0.0094) and bladder cancers with high grade dysplasia (p=0.0000234), the absence of a relationship between the level of PDGFR_a+β and clinical and morphological characteristics in bladder cancer.

Our results confirm the heterogeneity of CAF in both bladder and prostate tumors and indicate that FAP is one of CAF subpopulation marker.

Considering that FAP is expressed in a population of CAFs that lead to resistance to treatment with immune checkpoint inhibitors in melanoma, the FAP marker may also be diagnostically significant for tumors of the genitourinary system, especially given the fact that bladder tumors are treated with the BCG vaccine.