EURURO Vol. 72 No. 4

625 656

Prostate Cancer
The Microbiome of the Prostate Tumor Microenvironment
Ilaria Cavarretta , Roberto Ferrarese y, Walter Cazzaniga Diego Saita Roberta Luciano`
Elisa R. Ceresola Irene Locatelli Laura Visconti [2_TD$DIFF] Giovanni Lavorgna Alberto Briganti
Manuela Nebuloni [3_TD$DIFF] Claudio Doglioni Massimo Clementi [2_TD$DIFF] Francesco Montorsi
Filippo Canducci [1_TD$DIFF] [4_TD$DIFF] Andrea Salonia y
a Division of Experimental Oncology/Unit of Urology, URI, IRCCS Ospedale San Raffaele, Milan, Italy; bUniversita` Vita-Salute San Raffaele, Milan, Italy;
c Microbiology Unit, IRCCS Ospedale San Raffaele, Milan, Italy; d
[5_TD$DIFF]Pathology Unit, IRCCS Ospedale San Raffaele, Milan, Italy; e Department of Biotechnology and
Life Sciences, University of Insubria, Varese, Italy; f Human Virology Unit, IRCCS Ospedale San Raffaele, Milan, Italy; g Pathology Unit, Department of
Biomedical and Clinical Sciences, L. Sacco Hospital, Universita` degli Studi di Milano, Milan, Italy
ava ilable at
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Article info
Article history:
Accepted March 21, 2017
Associate Editor:
Christian Gratzke
Keywords:
Microbiome
Propionibacterium acnes
Prostate cancer
Tumor microenvironment
Staphylococcus spp.
Streptococcus spp .
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Abstract
Background: The advent of molecular-based methods of identification and characteri-
zation of complex microbial populations has led to a new era of microbial discovery. A
detailed and comprehensive analysis of the microbial ecosystem of the pathologic and
healthy prostate tissues has not been yet reported.
Objectives: To characterize the microbiome possibly associated to the pathologic pros-
tate microenvironment.
Design, setting, and participants: The microbiome profile of tumor, peri-tumor, and
nontumor tissues was assessed on 16 radical prostatectomy-specimens.
Outcome measurements and statistical analysis: Microbiome analysis was assessed by
massive ultradeep pyrosequencing. Bacteria load was expressed as a percentage of the
total number of bacteria. The statistical significance of differences among specimen-
groups was tested with Friedman’s test (Dunn posthoc test) and Wilcoxon rank-sum
test.
Results and limitations: Three phyla, six classes, nine orders, 14 families, and 11 genera
were above the set threshold value of 1%, respectively. Significant differences in specific
microbial populations among tumor/peri-tumor and nontumor prostate specimens
were observed at certain taxonomic levels. Among genera, Propionibacterium spp.
were the most abundant. Staphylococcus spp. were more represented in the tumor/
peri-tumor tissues (p < 0.05). The restricted number of specimens represents a poten-
tial limitation.
Conclusions: The prostate contains a plethora of bacteria, which set themselves within
the gland with a distribution dependent on the nature of the tissue, thus suggesting a
possible pathophysiological correlation between the composition of the local microbial
niche and the presence of the tumor itself. Future studies will help to clarify the role of
these specific bacteria and their potential to be exploited as new biomarkers.
Patient summary: The pathological prostate is populated by specific microbial popula-
tions, whose distribution varies according to the nature of the tissue. This finding opens
interesting perspectives for the identification of novel therapeutic approaches and
biomarkers.
# 2017 European Association of Urology. Published by Elsevier B.V. All rights reserved.
y These authors contributed equally to this paper.
* Corresponding author. Microbiology Unit, IRCCS Ospedale San Raffaele, Via Olgettina 60, Milan
20132, Italy. Tel. +39 02 2643 4284; Fax: +39 02 2643 4284.
E-mail address: (F. Canducci).
0302-2838/# 2017 European Association of Urology. Published by Elsevier B.V. All rights reserved.