Characterization of fecal microbiome in biopsy positive prostate cancer patients

To characterize the fecal microbiome in newly diagnosed prostate cancer patients.

Forty-nine consecutive patients who were referred for trans rectal prostate biopsy were tested. Patients who received antibiotics 3 months prior to the biopsy, patients with history of pelvic irradiation, prostate or colon cancer, inflammatory bowel disease and urinary tract infection were excluded. A rectal swab was obtained just prior to the biopsy, immediately placed in a sterile tube and kept in -80°C. Sequencing was performed for the 16S rRNA 515F + 806R gene fragment using the QIIME2 software. Analytic tests included Beta diversity (Weighted Unifrac, Unweighted Unifrac, Bray-Curtis), Alpha diversity (Faith, Evenness), Taxa bar plots and PCoA plots.

Forty-five samples were suitable for analysis with at least 8000 readings per sample. All patients were Caucasian. Twenty patients had prostate cancer and 25 had benign prostates (BPH). Among prostate cancer patients, Gleason Score was 3 + 3 in 11 patients, 3 + 4 in 5, 4 + 3 in 3, and 4 + 4 in 2. There was no statistical difference in demographic parameters between the groups. We identified over 1000 bacterial species, typical for the colonic microbiome. No significant differences in bacterial populations were found between prostate cancer versus benign prostate patients nor between age groups or between subgroups of Gleason or International Society of Uro-pathology (ISUP) scores.

Although the microbiome has previously been shown to have an impact on the human microenvironment and cancer risk, we could not demonstrate a significant difference between the flora diversity of newly diagnosed prostate cancer patients and BPH patients. Further research into distinct bacterial metabolic pathways may reveal unique risk factors for prostate cancer.