The presence of chronic inflammation in benign prostate tissue was associated with high-grade, or aggressive, prostate cancer. This association was found even in those with low prostate-specific antigen (PSA) levels, according to a new study.
An analysis of prostate tissue biopsies collected from some participants of the placebo arm of the Prostate Cancer Prevention Trial (PCPT) found that those whose benign prostate tissue had chronic inflammation had 1.78 times higher odds of having prostate cancer, and 2.24 times higher odds of having an aggressive disease (characterized by Gleason sum of seven to 10), compared with those whose benign prostate tissue had no inflammation. This study was published in Cancer Epidemiology, Biomarkers & Prevention (2014; doi:10.1158/1055-9965.EPI-13-1126).
“We had the unique opportunity to investigate biopsy tissue from patients who had no indication to prompt a biopsy,” said Elizabeth A. Platz, ScD, MPH, professor in the Department of Epidemiology at the Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland. “Participants in the PCPT who were not diagnosed with prostate cancer during the trial were recommended to undergo prostate biopsy at the end of that trial, which meant that prostate tissue was available not just for men who had the diagnosis of prostate cancer, but also for those who did not have the diagnosis.
Between 1993 and 1997, 18,882 men who were at least 55 years old and had normal digital rectal examination (DRE) findings with a serum PSA of 3 ng/mL or less, were recruited to the PCPT. All participants completed questionnaires that included demographics, lifestyle, and medical factors, and were followed for 7 years after they were randomly assigned to receive either finasteride or placebo.
From the placebo arm of this study, Platz and colleagues sampled 191 prostate cancer cases and 209 frequency-matched controls for whom biopsy tissue was available. They conducted histopathologic evaluations of the biopsy samples to identify the prevalence and extent of inflammation, and types of inflammation, ie, acute or chronic inflammation.
The researchers found that 86.2% of cases and 78.2% of controls had at least one biopsy core with inflammation, most of which was chronic, and this difference was statistically significant. They also found that the association between chronic inflammation and aggressive prostate cancer did not change after adjusting for known risk factors including body mass index, pack-years of cigarettes smoked, and history of diabetes.
In addition, this association held true even among men whose PSA levels were less than 2 ng/mL. “We detected chronic inflammation in prostate tissue of men who had prostate cancer but had PSA levels lower than 2 ng/mL, and thus our work supports an association between inflammation and prostate cancer that is not explained by PSA-associated detection bias,” said Platz.
Among men whose PSA levels were less than 2 ng/mL at the time of biopsy, those whose prostate tissue had inflammation had 4.11 times higher odds of having aggressive prostate cancer, compared with those whose prostate tissue did not have any inflammation.