A new study has found that Propionibacterium acnes is more common in the prostate tissue of men with prostate cancer, suggesting that the bacterium plays a role in the development of the disease.1 The study, published in Infectious Agents and Cancer, adds to a growing body of evidence that chronic inflammation may promote prostate carcinogenesis.

“Since inflammation is commonly observed in prostate tissue, the aim was to address the question of whether an infectious agent is able to cause inflammation, and to thereby act as an etiological factor for prostate cancer development,” said lead author Sabina Davidsson, PhD, of Orebro University in Sweden, in an email to Cancer Therapy Advisor. “A major strength in this study was the inclusion of prostatic tissue from men without prostate cancer, addressing a significant limitation of previous investigations.”

One hundred men diagnosed with prostate cancer who were undergoing radical prostatectomy were recruited as study subjects. Eighty-seven men undergoing surgery for bladder cancer, who had no histology of prostate cancer, were included in the study as control subjects; of these, 37 were later found to have signs of prostate cancer, and were separated into a third group dubbed “controls with prostate cancer.” Researchers took 6 biopsies from each patient’s prostate gland at the time of surgery, and cultivated the samples to determine the prevalence of P. acnes.

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It was found that P. acnes was significantly more common in the prostate tissue of men who were diagnosed with prostate cancer: 60% of the study group, 35% of the controls with prostate cancer group, and 26% of the control group had P. acnes present in prostate tissue. Median prostate-specific antigen (PSA) levels were 6.75 for men with P. acnes presence and 6.0 for those without.

A multivariate analysis showed that men with P. acnes in their prostate tissue were over 4 times more likely to have a prostate cancer diagnosis than those without, even after adjusting for factors such as age and smoking.

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“We were also able to show an increased proliferation and cytokine and chemokine secretion in normal prostate cells infected with P. acnes,” said Dr Davidsson. “This may indicate that P. acnes has a role in prostate cancer development.”

In previous studies, P. acnes was found to cause epithelial cells in the prostate to secrete cytokines and chemokines. “These inflammatory markers are critical for a sustained inflammatory response, and both are thought to play an important role in the development of…prostate cancer,” they wrote.