Ces Urol 2026, 30(3):126-131 | DOI: 10.48095/cccu2026018

Intratumoral microbiome in clear cell renal cell carcinoma – a new factor in the tumor microenvironment

Peter Polaček¹, Vojtěch Fiala¹, David Feldmar², Martin Matějů³, Otakar Čapoun¹, Viktor Soukup¹

¹ Urologická klinika 1. LF UK a VFN v Praze

² Onkologická klinika 2. LF UK a FN Motol a Homolka, Praha

³ Onkologická klinika 1. LF UK a VFN v Praze

Clear cell renal cell carcinoma (ccRCC), is the most common histological subtype of renal cell carcinoma and represents a significant oncological burden with particularly high incidence in European countries. In recent years, research has increasingly focused on the tumor microenvironment, which also includes the intratumoral microbiome – microorganisms present directly within tumor tissue. The aim of this review is to summarize current knowledge regarding the composition of the intratumoral microbiome in ccRCC, its relationship with the tumor immune microenvironment, and its potential prognostic significance. Available studies confirm the presence of bacterial DNA within ccRCC tumor tissue and demonstrate differences in microbial composition compared with adjacent non-tumorous tissue, including reduced alpha diversity. Specific microbial genera associated with overall survival and with patterns of immune cell infiltration have been identified. Some microorganisms appear to be linked to antitumor adaptive immune responses, whereas others are associated with an immunosuppressive tumor microenvironment and unfavorable prognosis. Current evidence also suggests a possible relationship between the microbiome and response to systemic therapy. Although existing evidence is largely observational and subject to methodological limitations, the intratumoral microbiome represents a promising field of research. Future studies should focus on methodological standardization and prospective validation of the clinical relevance of microbial signatures in patients with clear cell renal cell carcinoma.

Keywords: clear cell renal cell carcinoma – intratumoral microbiome – tumor microenvironment – alpha diversity – immunity – prognosis –\\r\\n16S rRNA sequencing – immunotherapy

Received: April 19, 2026; Revised: May 26, 2026; Accepted: June 8, 2026; Published: September 21, 2026