Men with chronic inflammation of noncancerous prostate tissue have nearly twice the risk of prostate cancer as those with no such inflammation, according to a study published recently in the journal Cancer Epidemiology, Biomarkers, and Prevention.1
The association between chronic inflammation and the presence of prostate cancer was even stronger among men with aggressive disease.
The case-control study compared the degree of inflammation in 191 prostate cancer cases and 209 matched controls without prostate cancer, all from the placebo arm of the Prostate Cancer Prevention Trial (PCPT), which was designed to determine whether treatment with finasteride prevents prostate cancer. PCPT participants underwent annual prostate examinations for 7 years; biopsy was recommended for those with elevated prostate-specific antigen (PSA) or abnormal digital rectal examinations (DREs). At study’s end, men not diagnosed with prostate cancer were asked to undergo a prostate biopsy, regardless of their PSA level or DRE results.
The researchers found that 86.2% of the men with prostate cancer and 78.2% of those who did not have the disease had inflammation in at least one biopsy core. Men with inflammation in at least one biopsy core had a sharply elevated risk of having prostate cancer (odds ratio [OR], 1.78; 95% CI, 1.04-3.06).
For cases of high-grade prostate cancer (Gleason sum, 7-10), it was found that the association between inflammation and cancer was even stronger (OR, 2.24; 95% CI, 1.06-4.71).
Previous studies have confirmed a high prevalence of inflammatory infiltrates in the prostate tissue of men with indications for prostate biopsy or disease of the prostate. This is the first study to examine the prevalence of inflammation in the prostate tissue of men without prostate conditions.
“Our study was designed to rule out the bias that would ordinarily exist between the way we detect prostate cancer and the presence of inflammation,” said Elizabeth A. Platz, ScD, MPH, a professor in the Department of Epidemiology at the Johns Hopkins University School of Public Health and the School of Medicine, Baltimore, MD, who led the research team. “Because inflammation makes PSA levels go up, men with inflammation are more likely to be biopsied. By doing more biopsies on these men, prostate cancer is more likely to be detected, even if inflammation is not a cause of prostate cancer.”
“What we’ve shown in this observational study is a clear association between prostate inflammation and prostate cancer, although we can’t prove that inflammation is a cause of prostate cancer,” Dr. Platz said.
Angelo M. De Marzo, another of the study authors, expressed surprise that so many men without prostate cancer were found to have inflammation in prostate tissue. “We knew going into this research that inflammation in the prostate is very common in men who have biopsies because of the higher PSA levels and other indicators of prostate cancer,” he said, “but we did not anticipate the high prevalence of prostate inflammation in men who didn’t have an indication for biopsy.”
Dr. De Marzo cautioned that, because inflammation in prostate tissue is so common, it is unlikely to find a role in the diagnosis of or screening for prostate cancer.
- Gurel B, Lucia MS, Thomson IM, et al. Chronic inflammation in benign prostate tissue is associated with high-grade prostate cancer in the placebo arm of the Prostate Cancer Prevention trial. Cancer Epidemiol Biomarkers Prev. 2014;23(5):1-10.