Prostate and urinary microbiomes in prostate cancer development: focus on Cutibacterium acnes

Prostate cancer (PCa) is one of the most prevalent malignancies among men, with its incidence steadily increasing worldwide. Recent advances in microbiome research have opened new avenues for understanding and treating PCa; however, studies focusing specifically on the prostate tissue microbiome remain limited. Evidence suggests that the microbial communities within PCa tissues exhibit significant diversity and regional variability, with certain bacteria potentially contributing to PCa initiation and progression through chronic inflammation. The prostate microbiome comprises not only bacteria but also viruses, fungi, and parasites, and its diversity is influenced by a complex interplay of genetic, environmental, and lifestyle factors. Methodological limitations and sample contamination further complicate the interpretation of microbiome data. The urinary microbiome is similarly diverse and shaped by multiple overlapping influences. Although urine, prostatic fluid, and prostate tissue are anatomically and functionally connected, whether urine and prostatic fluid can accurately reflect the prostate tissue microbiome remains to be conclusively determined. Among the microorganisms detected, Cutibacterium acnes is frequently identified in prostate tissue, urine, and prostatic fluid from PCa patients. This bacterium is known to elicit inflammatory responses through various pathways, potentially impacting tumorigenesis and cancer progression. Nevertheless, findings across studies remain inconsistent. Further research is necessary to elucidate the underlying mechanisms by which the microbiome influences PCa. Such efforts may offer novel insights and strategies for the diagnosis, treatment, and prevention of this disease.