Premalignant Prostate Lesion(PIN) of the Prostate

Recently, you underwent a prostate biopsy because of a suspicion that you have a prostate malignancy. Over the past few years we have learned a great deal about the various types of prostate problems that may occur. Saying that prostate biopsies are either benign or malignant is a simplification of a very difficult and complex task. Prostate tissue can present with many different findings and the pathologist's job to interpret these findings is difficult in many cases. Recently, we have been able to determine that premalignant prostate lesions exist. This means that cancer is NOT present, but the changes seen under the microscope suggest that cancers MAY develop later on. We have come to call these findings 'prostatic intra-epithelial neoplasia' or 'PIN.' The pathologists will rate or grade PIN lesions from 1 to 3 with 1 being only slightly unusual and grade 3 being very unusual and very close to being called cancer or malignant. More recently, PIN has been reclassified as Low grade or High grade, with PIN 1 being Low grade and PIN 2 and 3 being High grade.

Patients whose biopsy specimens contain PIN may or may not have a PSA (Prostate Specific Antigen) value, which is higher than those with only normal tissue. Again, these findings suggest that PIN is intermediate between normal prostate enlargement and cancer. For you, the patient, and us, the clinicians, the important question is--what is the risk of subsequent prostate cancer in a patient in whom we have found PIN? It appears that in patients with high grade PIN that the chances of developing cancer is probably in the range of 35-40 percent or more within a five-year period. In patients with Low grade PIN, it appears that the risks are in the range of 15 to 20 percent over a ten-year period. In patients where biopsies had no signs of PIN, the chance of developing a cancer in the future is about 10 percent. Obviously, the more severe the PIN changes, the higher the risk for later development of cancer.

At this time we do not believe that patients with PIN should be treated as though they have cancer, because not all patients will, in fact, develop cancer. It must be recognized that these patients are more at risk than patients without PIN, and this only means that we need to follow PIN patients very closely. Because prostate ultrasound and PSA are relatively new techniques, we are still learning more and more about prostate pathology, and as time goes on our views and decisions might change. At this point, however, we will continue to follow you closely while keeping abreast of all the new developments. Can PIN be eliminated or be prevented from becoming cancerous? We are not certain, but research is being done to see if medications such as finasteride can turn PIN back to normal.

Based on these findings, our recommendations to you are as follows:

  1. We should be performing repeat biopsies on patients with severe, extensive PIN. This may be any time between three and twelve months, depending on your circumstances. The follow-up biopsies will give us more information about what is going on in your prostate, and as long as the PIN is persistent we need to continue to follow you very closely.
  2. We need to monitor your PSA levels and do rectal exams, and this should be done at a minimum of six-month intervals.
  3. If the PSA rises or rectal exam changes, a repeat biopsy would be mandated at that time.