When Perineural Invasion Is Found on Prostate Biopsy
What do you do if your prostate biopsy comes back showing perineural invasion (PNI)? Recently, Hopkins scientists have learned something important about this finding: Many doctors, as well as their patients, don't understand it. New tables developed at the Brady may help.
"The finding of PNI on a prostate biopsy has long been felt to be a risk factor for the extension of cancer outside of the prostate gland," says Alan W. Partin, M.D., Ph.D., the David Hall McConnell Professor in Urology and Director of the Brady. In fact, one recent metaanalysis found that men who have PNI on a prostate biopsy have about a twofold higher risk of having cancer that has spread beyond the prostate than men who don't have it.
However, low-volume cancer seems to play by different rules. "A study from Johns Hopkins of men with very low-risk prostate cancer – men who were otherwise candidates for active surveillance, but who chose to have surgery – found no association between PNI and the risk of cancer spreading outside the confines of the prostate gland," Partin says. "Taken together, these studies suggest that the urologic community has yet to fully understand the prognostic significance of PNI on a prostate biopsy, especially among men with low-volume disease."
Seeking to help men with this finding who are trying to choose the treatment that's best for them, Partin and colleagues have developed new risk tables. These tables – like the well-known Partin Tables, except focused on PNI – set forth the more exact risk of having cancer that is not confined to the prostate. Using the PSA , clinical T stage, biopsy Gleason score and tumor volume – "the volume is really the key to this work," explains Partin – the tables estimate risks of having non-organ-confined disease. "Using these tables, men and their physicians can now more accurately judge the risk of having cancer located outside of the prostate, thus allowing for more informed decisions about treatment." The analysis was done by Michael Gorin, M.D., Heather Chalfin, M.D., Jonathan Epstein, M.D., Zhaoyong Feng, Ph.D., Partin, and Bruce Trock, Ph.D. "The study's first author, Michael Gorin, is a junior resident at the Brady, and the second author, Heather Chalfin, just started her internship in urology here at Hopkins," notes Partin.