PSA levels, prostate cancer risk, and diagnosis in the “real world”

For all of the academic literature and the recommendations of guideline-generating organizations on testing, diagnosis, and management of prostate cancer, urologists out in community practice may show considerable variation in their clinical practice patterns.

Lawrentschuk et al. recently conducted a survey of the practice patterns of Canadian urologists with respect to the detection of prostate cancer. The primary focus of their survey was to assess those factors that were crucial to the decision to recommend that a patient undergo a transrectal ultrasound-guided prostate biopsy because of the patient’s potential risk for prostate cancer.

The survey apparently used case scenarios of patients with a variety of ages, family histories, ethnicities, and PSA levels, and the urologists were asked to indicate when they they would recommend a biopsy in each case scenario. All 360 active urologists who belong to the Canadian Urological Association were asked to participate in this online survey; apparently 125/360 urologists actually completed the questionnare, with the following results:

  • 67 percent of respondents indicated men should be tested for prostate cancer starting at age 50-60.
  • 27 percent indicated that testing should be initiated in men aged 40-50 years.
  • 77 percent of the respondents would continue to test men of >75 years of age.

The abstract also gives two specific case examples:

  • In the first case, the patient is a 65-year-old male who has no known risk factors and a normal DRE.
    • 56 percent of the respondents would offer a biopsy if his PSA level was 4.5 ng/ml.
    • 35 percent would offer a biopsy if his PSA was 3.5 ng/ml.
    • 10 percent would offer a biopsy if his PSA was 2.5 ng/ml.
  • In the second case, the patient is a 45-year-old man, also with no known risk factors and a normal DRE.
    • 94 percent of the respondents would offer a biopsy if his PSA level was 4.5 ng/ml.
    • 77 percent would offer a biopsy if his PSA was 3.5 ng/ml.
    • 33 percent would offer a biopsy if his PSA was 2.5 ng/ml.
  • The decision to offer a patient a biopsy among this group of clinicians appears to be much more dependent upon younger age (odds ratio [OR], 4.3-20.6) and higher PSA level  (OR, 4.4-34.9) compared to family history (OR, 3.3) or ethnicity (OR, 1.8), and this variation was highly statistically significant (P < 0.0001)

The authors conclude that — among this group of community Canadian urologists — patient age and PSA level appear the driving factors in recommendation of a biopsy, and that a significant proportion of these urologists would still not offer a biopsy at the traditional PSA cutoff of 4 ng/ml for men with no other known risk factors.

Two things are of great interest to The “New” Prostate Cancer InfoLink in trying to interpret this study.

The first is what appears to be a logical inconsistency between the relatively high proportion of Canadian urologists who would not recommend a biopsy for a 65-year-old man with a PSA of 4.5 ng/ml (44 percent) as compared to the very high percentage of Canadian urologists who would happily continue to offer PSA testing to men over the age of 75 (77 percent). Why is one giving PSA tests to asymptomatic 75-year-olds when one wouldn’t have been willing to biopsy them when they were 65?

The second is the apparent message to Canadian men that if they have significant concerns about a future risk for prostate cancer, based on such things as family history or ethnicity, they would be wise to start asking for PSA tests in their 40s rather than their 50s!

9 Responses

  1. This study and others like it don’t ask the urologist to consider the risk of iatrogenic metastases (mets created by the biopsy), especially with repeated biopsies.

  2. Dear Clark:

    In order to get a clear idea of whether there is any significant risk of iatrogenic metastasis as a consequence of a prostate cancer biopsy, we would probably have to identify and track data over about 15+ years from (a) about 10,000 prostate cancer patients who had a positive biopsy for cancer to see who and how many got metastatic disease, and (b) about 10,000 patients who were at risk for prostate cancer but never received a biopsy and were subsequently diagnosed with metastatic disease.

    Quite apart from the fact that this study would probably be unethical, I find it hard to know how one could possibly track that many patients who wouldn’t want to have a biopsy and get appropriate treatment if they were at known risk for prostate cancer.

    I understand that you are concerned about the theoretical possibility of iatrogenic metastasis subsequent to a prostate biopsy, but since I know of no documented cases of this event, it is hard to know either how to help you or why one should try to do an impossible trial to prove its existence (which is going to be extremely rare at best). You are applying what is sometimes referred to as “magical thinking” to give “reality” to a concept which is not supported by available clinical data.

  3. The question of iatrogenic metastasis being associated with biopsy procedures comes up often on sites and in mails to me off my site.

    In the absence of studies — and I agree with Sitemaster about the impracticality of such studies being developed — I usually suggest that some common sense be applied.

    Literally millions of biopsy procedures have been carried out since the inception of PSA testing in the US and around the world. IF biopsy procedures were associated with metastasis, then it would be a logical expectation to see a rise in the diagnois of metastatic disease, but there is no such rise. In fact the reverse is true with incidence rates moving downwards.

  4. Good reply sitemaster, since it is the only reasonable reply to those who come to their own conclusion that if there is cancer, it will be spread by biopsy, when there is no significant data to support such conclusions. The question posed is which is safer when PSA level is increasing and/or DRE determines non-palpable prostate or nodule presence is determined — find out if you have developing cancer and its extent by biopsy, or disregard biopsy and either move to an invasive treatment when it may not be required or wait indefinitely because of fear of the “unknown” and permit the cancer to become aggressive and metastases occur?

  5. Where PSA velocity is low (4.5 to 5 ng/ml rise over 5 years), but PCA3 score is high 78, no positive DRE or family history, if there is risk of aggressive cancer based on PCA3, would it be logical to go directly to radical prostatectomy to avoid even small risk of iatrogenic metastasis from biopsy?

  6. Not in my world.

  7. If the theory that the piercing of the prostate gland can let forth a flood of cancer cells that cause the disease to spread, how many more cells would be released in the excising of the entire gland?

  8. I am 77 years and feel good. I was referred to a urologist by my primary care doctor because my PSA went to 4.5 from about 3.5 ng/ml. Do I need biopsy or is there other suggestion?

  9. Dear Mel:

    A PSA level of 4.5 ng/ml in a man of your age is well within the normal range. There is no reason to believe (necessarily) that you have clinically significant prostate cancer. This PSA level could be “nothing” or it could be associated with simple enlargement of your prostate.

    You certainly could have a biopsy if you wanted to have one, but there are all sorts of reasons for you to not have a biopsy — starting with “What would you want to do if the biopsy showed a tiny amount of tissue positive for low-risk prostate cancer that was high;ly unlikely ever to bother you in your lifetime?”

    We are in no position to advise you what you need to do. That is up to you and your doctors. However, if I was in the position you describe, I certainly wouldn’t do anything else until I had had another PSA test in a few months time. Your PSA level might fall again.

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