Uncovering the role of urinary microbiota in urological tumors: a systematic review of literature

Purpose Urinary microbiota has been found to play a key role in numerous urological diseases. The aim of this systematic review is to depict the role of urinary microbiota in the pathogenesis, diagnosis, prognosis, and treatment of urological tumors, including bladder cancer (BCa), prostate cancer (PCa) and renal cell carcinoma (RCC). Methods A systematic PubMed and Scopus search was undergone from inception through June 2021 for studies investigating urinary microbiota alterations in urological tumors. Study selection followed the PRISMA statement. Phylum, family, genus and species of each bacterium in cancer patients and controls were recorded. Results Twenty-one studies with 1194 patients (748 cancer patients and 446 controls) were included in our final analysis. Certain bacterial phylum, family, genus, and species were more predominant in each of BCa, PCa and RCC patients compared to controls. Abundance and specificity of urinary microbiota were prognosticators for: (1) recurrence, distinguishing recurrent from non-recurrent BCa, (2) disease stage, distinguishing non-muscle invasive from muscle invasive BCa, and (3) disease grade, distinguishing high- vs. low-grade PCa and BCa. Dietary, environmental and geographic patterns influenced urinary microbiota. Urinary microbiota of benign prostatic hyperplasia was different from PCa. Conclusion Urological cancer patients have an altered urinary microbiota compared to controls. This may predict recurrence, disease stage and disease grade of these tumors. Further prospective studies are needed to depict a potential influence on therapeutic outcomes.