Prostate cancer news reports: Tuesday, August 11, 2009

Today’s news items deal with:

  • The effect of dutasteride on the results of PCA3 tests
  • How common is the TMPRSS2 fusion gene in men with prostate cancer in North America?
  • Can prostate biopsy data predict laterality of prostate cancer with accuracy?

Dutasteride is commonly used in patients who have benign prostatic hyperplasia (BPH) and/or are at risk for prostate cancer. It is therefore important that physicians and their patients understand the influence of dutasteride on new prostate cancer markers. Based on an exploratory (pilot) study in just 25 patients, an initial report by van Gils et al. suggests that treatment with dutasteride has a variable impact on the results of PCA3 testing. They note that, “This should be taken into account while using PCA3 in diagnostics.” It should be noted thatthe other effects of dutasteride in this study were consistent, as it rapidly reduced serum dihydrotestosterone levels by ≥ 90 percent, increased serum T by 20-30 percent over time, halved the patients’ serum PSA levels over time, and decreased prostate volume by 10-16 percent.

A study by Mosquera et al. in 100 patients with prostate cancer and 34 patients with BPH has shown that fusion of the TMPRSS2 prostate-specific gene with the ERG transcription factor was  found in 46 percent of the men with prostate cancer and 0 percent of the men with BPH. In other words, this is a common and apparently specific genetic rearrangement in certain North American men with prostate cancer. However, the study also showed that (a) there was no significant association between occurrence of this genetic rearrangement and the Gleason score and (b) non-Caucasian patients were less likely to have a positive fusion status. It is therefore hard to know exactly how to interpret the clinical significance of this finding, based on the data avilable so far.

Fota et al. report that preoperative needle biopsy data have limited correlation with the laterality of significant cancer and positive surgical margins in final pathology specimens after laparoscopic radical prostatectomy (LRP). In  other words, even though the patient’s initial biopsy result suggests the presence of cancer in only the left or the right lobe of the prostate, it is very common to actually find cancer in both lobes at the time of surgery.

7 Responses

  1. “Amen” to the last sentence of the “Conclusion” of the TMPRSS2 ERG testing. Interesting that in your report for this date that dutasteride/Avodart is also mentioned regarding its effect if also testing PCA3. In my research, I have found that dutasteride/Avodart plays a role in gene regulation, up-regulating a good gene, IGFBP3, and down-regulating two bad genes, TMPRSS2 and TFF3, with the result that prostate cancer cell apoptosis as well as inhibition of prostate cancer cell proliferation occurs. Another “plus” for dutasteride/Avodart inclusion in androgen deprivation therapy (ADT).

  2. With respect to the paper by Fota et al.:

    These data continue to underscore the limitations of conventional 12-needle TRUS biopsy.

    Those contemplating active surveillance or focal therapy would do well to consider mapping biopsy.

  3. We would certainly agree with this suggestion in regard to focal therapy. However, mapping biopsies are probably only appropriate in a subset of newly diagnosed patients considering active surveillance — most particularly those who are younger and are therefore more likely to need curative treatment for localized disease after some period of surveillance.

    In addition, we are noting an increasing incidence of what would seem to be excessive application of mapping biopsy procedures (a case of a mapping biopsy with 99 cores removed was reported on this site the other day). The “New” Prostate Cancer InfoLink is very concerned by this trend because excessive biopsying of the prostate is tantamount to radical surgery, and can lead to all sorts of side effects in itself.

    The application of mapping biopsies is certainly appropriate for carefully identified patients, but over-application of this technique is just as inappropriate as the over-application of surgery, radiation, and every other form of therapy.

  4. Mapping biopsies (5 mm grid) take ~ prostate volume in CC +20 needles. Mr. 99 Cores must have (had?) quite a gland: a lemon, not a walnut.

    Most men require a day on a catheter afterward — an outpatient procedure, not radical surgery. Practitioners report that complications are usually minor and self correcting.

    Fota’s paper and others in a similar vein must give any man on surveillance cause for concern. Until an improved method of imaging is developed, mapping biopsy will remain the best way available to determine the nature and location of prostate cancer.

  5. Steve:

    I think you are missing the point of what I am saying. You are describing one type of mapping bipsy: a 20-core mapping biopsy. But that is just one type of biopsy that is being used. Some physicians are using far more intense types of mapping biopsy, and there was no suggestion that “Mr. 99 Cores” had a particularly large prostate (although it is possible that that was the case).

    A 20-core mapping biopsy is a perfectly reasonable thing to do in appropriately selected patients. That is not what I am expressing concern about. My concern is with a small but growing number of physicians who are now using the excuse of mapping and saturation biopsy techniques to take 30, 40, 50 and more cores at a time. In at least some of these cases, this looks to me like a sure-fire way to find some amount of prostate cancer — thus justifying the subsequent need for treatment in men who may just be being taken advantage of. In the case of “Mr. 99 Cores” they found 1 positive core (Gleason grade 3 + 3 = 6) among the 99 taken.

  6. Mike,

    Sorry that we are getting wrapped around the biopsy needle.

    What I was trying to say was that you can roughly compute the numbers of needles it will take to complete a 5 mm grid mapping biopsy by taking prostate size in cubic centimeters and adding 20 to that.

    Mr. 99 may have started out with a 79 cc prostate — a monster.

  7. I should also add, I hope that Mr. 99 Cores didn’t panic over that one core and either went on active surveillance or opted for focal treatment — depending on his age and expected life span.

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