New studies provide guidance.

When is active surveillance (AS) safe, and when is it better to seek curative treatment for prostate cancer instead? Findings from recent Hopkins-led studies provide guidance for men with specific biopsy findings. This work was published in the Journal of Urology.

Perineural Invasion (PNI)

“Perineural invasion (PNI) is a term used to describe cancer invading the space surrounding small nerve fibers within the prostate,” says urologist Christian Pavlovich, M.D., the Bernard L. Schwartz Distinguished Professor in Urologic Oncology and Director of the Prostate Cancer Active Surveillance Program. Most men with favorable-risk prostate cancer – Grade Group 1 (GG1; Gleason pattern 3+3, the lowest grade) – don’t have PNI. Thus, says Pavlovich, “it is a significant finding.”

In one study, Pavlovich and colleagues found that the presence of PNI on surveillance biopsy was associated with a greater chance of the cancer turning more aggressive during surveillance.  “In addition, PNI was associated with prostate cancer actually being found outside the prostate when it came time for radical prostatectomy.” However, he notes, the presence of PNI did not impact the long-term prognosis of these patients “because the surgery was thankfully curative.”

Grade Group 2 Cancer

What happens if you’re diagnosed with GG1 cancer, you begin AS, and in a follow-up biopsy, Grade Group 2 (GG2; Gleason pattern 3+4 or 4+3) cancer is found? “When this happens, men often leave AS,” says pathologist Ezra Baraban, M.D. But do they have to?

In a second study, Baraban and colleagues sought to identify subgroups of men “who can safely remain on AS,” even though they have some GG2 cancer . They studied the prostate tissue of men who started on AS but eventually had prostatectomy. “We found that 57 percent of men who were reclassified to GG2 showed favorable pathologic findings at prostatectomy.” In fact, “GG2 patients with low PSA density and without PNI had a lower risk for adverse pathology at prostatectomy than GG1 patients who did have these risk factors. Therefore, reclassification to GG2 alone should not disqualify men from continuing on AS.”

Pathological findings that signified higher risk included having a percentage of Gleason pattern 4 approaching 50 percent and large cribriform morphology or intraductal carcinoma. “Conversely, in the absence of other worrisome findings, patients with low PSA density and without PNI are particularly suitable candidates for remaining on active surveillance despite reclassification to GG2.” This is reassuring news for men with favorable intermediate-risk cancer on AS.