PREMALIGNANT PROSTATE LESIONS --P.I.N. OF PROSTATE
(PROSTATIC INTRAEPITHEAL NEOPLASIA)
Recently, you underwent a prostate biopsy because of a suspicion that you might
have a prostate malignancy. Over the past few the 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 and High grade,
with PIN 1 being Low grade and PIN 2 & 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 at risk higher than risks found in patients without PIN, and this only means that we need to follow PIN patients very closely. 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, dutasteride, or toremifene and other drugs can reduce your risk. (The first two are available now, the third drug is still experimental).
Based on these findings, our recommendations to you are as follows:
We should be monitoring PSAs regularly and performing repeat biopsies on patients with severe PIN at regular intervals. This may be anytime between three to 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. If the PSA rises or the rectal exam changes, a repeat biopsy would be mandated at that time.
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Consider joining a study using drugs that might reverse the PIN back to normal. Some recent studies which are still ongoing show promise, most specifically with a drug called 'toremifine'.