Written by Charlotte Harrison, Science Writer
Finding biomarkers in the urine of patients with aggressive prostate cancer would help identify the disease at an early stage. A new paper in the European Urology Oncology now shows that men with specific anaerobic bacteria in their urine or prostate tumour tissue are more likely to develop aggressive disease. As such, these bacteria could be a new prognostic biomarker.
In the study, the authors assessed the microbiomes from patients using anaerobic culture, 16S ribosomal amplicon sequencing, mRNA sequencing, and whole genome DNA sequencing to detect bacteria in urine and prostate cancer tissue. They used nonbiased ‘tree of life’ methodology to isolate and classify novel bacteria, and also searched for associations between the presence of bacteria and prostate cancer risk.
Bacteria linked to disease progression
Characterisation of the bacterial community from patients identified four novel bacteria (Porphyromonas sp. nov., Varibaculum sp. nov., Peptoniphilus sp. nov. and Fenollaria sp. nov.) that were frequently found in patient urine.
Then, having identified putative novel species, the authors went on to identify bacterial genera associated with high-risk prostate cancer. Overall, five genera were commonly found in high abundance in high-risk and advanced or metastatic disease. These genera were anaerobes — Fenollaria/Ezakiella, Peptoniphilus, Porphyromonas, Anaerococcus and Fusobacterium — and included three of the novel isolates.
The authors termed these genera the ‘anaerobic bacteria biomarker set’. Men who had these bacteria in their urine were more than twice as likely to see their early-stage cancer progress to advanced disease.
But do the bacteria cause cancer?
This study indicates that the anaerobic bacteria biomarker set has prognostic potential. But the study didn’t show if the bacteria can cause prostate cancer. Further research is needed to determine this, dissect out the pathogenetic processes, and subsequently identify treatments to eliminate the anaerobic bacteria.
Rosalind Eeles, an author of the study noted that “It is not yet known if [the bacteria] are causative but if this could be proven then we have a potential route for prevention. The way that we may be able to prove this is to look to see if these organisms are never found in prostate samples that have no cancer.”
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