Men who show signs of chronic inflammation in non-cancerous prostate tissue may have nearly twice the risk of actually having prostate cancer than those with no inflammation. The link between persistent inflammation and cancer is even stronger for men with so-called high-grade prostate cancer — those with a Gleason score between 7 and 10 — indicating the presence of the most aggressive and rapidly growing prostate cancers.

Although inflammation is too widespread in men to be used as a diagnostic tool for prostate cancer, there is a clear association between prostate inflammation and prostate cancer.

Research is ongoing about what causes prostate inflammation, how it may contribute to prostate cancer, and whether this inflammation may be prevented. The study that first connected the dots between inflammation and prostate cancer was led by researchers from the Johns Hopkins Kimmel Cancer Center.

Most of the data come from analysis of information about men in the placebo-taking group of the Southwest Oncology Group’s Prostate Cancer Prevention Trial. That trial, designed to learn whether the drug finasteride could prevent prostate cancer, included biopsies for prostate cancer at the end of the study even if there were no suspicious signs of cancer such as high prostate specific antigen (PSA) levels.

Researchers have examined possible links between inflammation and prostate cancer in other studies, but the previous studies began by sampling tissue from men who had some cause to undergo a biopsy. The Johns Hopkins study was designed to rule out the bias that would ordinarily exist between the way we detect prostate cancer and the presence of inflammation.

Inflammation normally makes PSA levels go up, so men with inflammation are more likely to have higher PSA and, with a rising PSA, they’re 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.

For the Johns Hopkins study, benign tissue samples taken from the biopsies of 191 men with prostate cancer and 209 men without cancer, examining the samples for the prevalence and extent of immune cells that indicate inflammation. The results showed that 86.2 percent of the prostate cancer patients had at least one tissue sample with signs of inflammation, compared to 78.2 percent of men without cancer.

Ultimately, men with at least one tissue sample showing signs of chronic inflammation had 1.78 times higher odds of having prostate cancer, and 2.24 times higher odds of having an aggressive cancer, the researchers concluded. The association held firm even in men with low PSA levels at the time of their biopsies.