Premalignant Prostate Lesions - Prostatic Intraepithelial Neoplasia (PIN)

Over the past few years, urologists have learned a lot about the different types of prostate problems that can occur. Saying that prostate biopsies are either benign (not cancerous) or malignant (cancerous) is a simple way of talking about something that takes a lot of work to figure out. Tissue that is biopsied can show many different things, and the pathologist’s job is to determine what those things mean, which is not always easy. Recently, urologists have found that pre-malignant (pre-cancerous) prostate conditions do exist. This means that cancer is NOT present, but the changes seen under the microscope lead us to think that cancers MIGHT develop later on. This is called prostatic intraepithelial neoplasia or PIN. The pathologists will assign a grade or rating to PIN lesions starting at 1, meaning only slightly unusual, and up to 3, meaning very unusual and close to being called cancer. Even more recently, PIN has been reclassified as “low grade” and “high grade” with PIN 1 being low grade and PIN 2 and 3 being high grade.

Patients whose biopsy specimens show PIN might or might not have a PSA result that is higher than those with only normal tissue. Again, this means that PIN falls somewhere between a normal, enlarged prostate and cancer. Meanwhile, the important question is – what is the risk of later prostate cancer in a patient who shows PIN or those pre-cancerous cells? It appears that in patients with high-grade PIN, the chance of developing cancer is about 35 to 40 percent in a five-year period. In patients with low-grade PIN, it looks as if the risk of developing cancer is about 15 to 20 percent over a 10-year period. In patients whose biopsies didn’t show any PIN, the chance of developing cancer in the future is about 10 percent. Obviously, the greater the PIN changes, the higher the risk for later cancer.

Right now, we don’t think that patients with PIN should be treated as though they have cancer, because not all patients will get cancer. We know that patients with PIN are at higher risk to develop prostate cancer than patients without PIN. This means only that we need to follow PIN patients more closely than we would other patients. Because prostate ultrasound and PSA are relatively new techniques, we’re still learning more about what can go wrong in the prostate, and, as time goes on, our decisions might change as we learn more. Right now, we continue to follow patients closely while keeping on top of all the new developments in the treatment of prostate conditions.

What should you do?
Here are our recommendations for patients with PIN:

• Those with high-grade PIN should undergo a prostate biopsy at regular intervals, usually between every three and 12 months, depending on circumstances. These biopsies will tell us what’s going on in your prostate.
• We need to monitor your PSA levels through blood tests and do rectal exams at least every six months.
• If the PSA rises or a rectal exam shows changes, a repeat biopsy then would be ordered.

For patient appointments, call (314) 362-8200 (Center for Advanced Medicine and Barnes-Jewish West County Hospital).