Abstract
<title>Abstract</title> <p> Purpose Prostate cancer (PCa) is a leading cause of cancer-related mortality in men worldwide. Chronic prostate inflammation, often associated with benign prostatic hyperplasia (BPH), is a recognized contributor to prostate carcinogenesis. Recent evidence suggests that urinary microbiota dysbiosis may play a role in this process and serve as a source of microbial biomarkers. Methods Here, we characterized the urinary microbiome in PCa and BPH patients compared to controls using targeted 16S rRNA gene sequencing. Results Urine samples from 68 male participants (22 PCa, 32 BPH, 14 controls) were analyzed. Significant differences in microbial diversity and composition were observed across the three group. BPH samples exhibited the highest alpha diversity, followed by PCa samples, while controls showed the lowest diversity (Shannon index, p = 0.001). PCa urines were dominated by <italic>Streptococcus, Gardnerella</italic> , and <italic>Klebsiella</italic> , whereas BPH urines showed higher abundances of pro-inflammatory anaerobic or microaerophilic bacteria such as <italic>Fusobacterium</italic> , <italic>Prevotella</italic> , and <italic>Campylobacter</italic> . Beta diversity analysis revealed distinct clustering of PCa samples (p = 0.001), significantly associated with <italic>Gardnerella vaginalis</italic> and <italic>Klebsiella pneumonia</italic> . Chemotherapy significantly altered the urinary microbiome, increasing the abundance of uropathogenic Proteobacteria (56.2%) ( <italic>Escherichia coli</italic> , <italic>Enterococcus faecalis)</italic> , opportunistic bacteria ( <italic>Finegoldia magna</italic> and <italic>Prevotella bivia)</italic> , and depleting beneficial bacteria <italic>Lactobacillus crispatus</italic> and <italic>Corynebacterium amycolatum</italic> . Conclusions This study identifies the urinary microbiome as a promising non‑invasive biomarker for prostate diseases. Microbial dysbiosis promotes pro‑inflammatory and uropathogenic bacteria and contribute to prostate inflammation and cancer progression, while chemotherapy further destabilizes this fragile ecosystem. Microbiota‑based probiotic supplementation, could help to restore microbial balance and support urogenital health in prostate diseases. </p>