What It Means When A Man's Prostate Cancer Biopsy Indicates Perineural Invasion

It's common for healthcare professionals to order biopsies for patients whom they suspect may have prostate cancer. A biopsy doesn't just rule out prostate cancer or show its presence, though. It can also help determine if the cancer may have spread beyond the prostate gland, such as near the nerves. In that case, the biopsy will show that there's perineural invasion.

"Perineural invasion means that cancer cells have been found surrounding or tracking along the nerves within the prostate," says Dr. Justin Houman, Tower Urology Men's Health and Assistant Professor Department of Urology at Cedars-Sinai Medical Center. That's important because the nerves run throughout the prostate tissue. Consequently, the presence of cancerous cells near the nerves can raise suspicions that the cancer has spread (or might spread) beyond the prostate gland. 

That said, Dr. Houman doesn't advise making treatment decisions based solely on a perineural invasion finding since it's just one of many factors used to create a patient's personalized prostate cancer treatment plan. Put simply, perineural invasion is a warning sign of prostate cancer possibly moving outside of the prostate gland; it's not automatic confirmation that the scenario is occurring.

How much does perineural invasion raise a man's chances of his prostate cancer metastasizing and moving into other areas of the body? That's what researchers investigated in a 2017 study published in Cancer Epidemiology, Biomarkers and Prevention. They tracked two groups: The first group consisted of 615 men who had opted not to treat their prostate cancer, while the second was made up of 849 men who had chosen to address their prostate cancer by undergoing radical prostatectomies. For men in both groups, receiving a biopsy result of perineural invasion was associated with a higher risk of dying from prostate cancer.

Knowing this, healthcare providers may recommend or discourage certain treatment options for their patients whose initial or later biopsies reveal perineural invasion. For example, some men might be interested in taking an active surveillance approach to their prostate cancer when they're initially diagnosed. And there's nothing wrong with that in certain cases, as research suggests that a monitoring approach may be as effective as treatment interventions. However, as Dr. Houman explains, active surveillance may be less appropriate for men who have been told their biopsies revealed perineural invasion, as it's a possible sign of a more aggressive cancer.

How else can men treat their prostate cancer if they're not good candidates for active surveillance due to a perineural invasion biopsy result? Dr. Houman says either surgery or radiation therapy might make sense, as might combining treatments for prostate cancer to improve outcomes. "Surgeons may be more cautious when evaluating nerve-sparing techniques during prostate removal." A surgical procedure like a radical prostatectomy does that because it removes all existing cancerous tissue, effectively helping surgeons achieve clear margins. 

Radiation therapy may be an attractive treatment if there are other high-risk features present, notes Dr. Houman. He adds that in some circumstances, providers may feel it's wise to give their patients androgen deprivation therapy, a type of hormone therapy, in addition to radiation therapy to further reduce the chance of cancer returning.

The key takeaway from Dr. Houman is that perineural invasion is one factor that can indicate more aggressive cancer behavior. But other tests, such as imaging scans and additional pathology findings, are typically performed to figure out if any cancer has moved beyond the boundaries of the prostate gland before determining what type of treatment makes sense. 

Accordingly, if your prostate cancer biopsy shows signs of perineural invasion, you can probably expect further tests to help inform your best route toward remission. And since figures from the National Cancer Society show that the five-year long-term survival rate for prostate cancer is 97.5%, remission may be a statistically achievable goal.