Making informed and sensible choices about PSA testing

A group of Australian researchers has developed a statistical model that may help men to be able to make better choices about their need for prostate cancer screening. But not everyone is going to agree with this point of view! At the same time, an article in the BMJ by a team of Harvard epidemiologists argues that the PSA test needs to be offered much more selectively and appropriately, and describes that change as “urgently needed.”

Howard et al. have used results from the latest population studies, and a range of other available data, to build a Markov model to predict the impact of annual PSA testing on risk for prostate cancer-specific mortality. Such information is likely to be helpful for some men and their doctors but may be confusing for others.

Howard and her colleagues sought to develop this information for men aged 40, 50, 60, and 70 years who were at low, moderate, and high risk for prostate cancer.

Their model compared patients who had annual PSA screening to those who did not using a 20 percent reduction of relative risk for prostate cancer mortality as a best-case scenario. In other words, their model assumed that men undergoing annual screening were 20 percent more likely not to die 0f prostate cancer than patients who didn’t have annual screening PSA tests. The model then estimated numbers of biopsies, prostate cancers, and deaths from prostate cancer per 1,000 men over 10 years and cumulated to age 85 years.

The results of this model show the following:

  • Benefits and harms vary substantially with age and familial risk.
  • In the case of 60-year-old men with low risk disease, Howard et al. estimate that, as an example, of 1,000 men screened annually and another 1,000 men who are not screened:
    • 115 men (11 .5 percent) in the screened group will undergo biopsy triggered by an abnormal PSA result.
    • 53 men (5.3 percent) in the screened group will be diagnosed as having prostate cancer over 10 years compared with 23 men diagnosed as having prostate cancer among the unscreened group.
    • Among screened men, 3.5 per 1,000 (0.35 percent) will die of prostate cancer over 10 years
    • Among unscreened men, 4.4 per 1,000 (0.44 percent) will die of prostate cancer over 10 years
  • For 1,000 men screened from 40 to 69 years of age, and compared with 1,000 unscreened men over the same time period:
    • There will be 27.9 prostate cancer deaths and 639.5 deaths overall by 85 years of age in the screened group.
    • There will be 29.9 prostate cancer deaths and 640.4 deaths overall by 85 years of age in the unscreened men.
  • Higher-risk men have more prostate cancer deaths averted but also more prostate cancers diagnosed and more related harms.

Howard and her colleagues conclude that men should be informed of the likely benefits and harms of PSA screening, and that their model-generated estimates can be used to support individual decision making.

At the same time, an analytical article in BMJ by Stark et al. argues that:

The introduction of prostate specific antigen (PSA) testing as a screening tool has transformed the clinical landscape of prostate cancer. Screening allows prostate cancer to be diagnosed many years earlier, offering hope that a newly detected cancer is still localized to the prostate when treatment is curative.

The BMJ article is discussed in some length on Medscape. In the Medscape article, both Stark and urologist Brantley Thrasher (a member of The “New” Prostate Cancer InfoLink’s Scientific Advisory Board) are at some pains to point out the distinction between the appropriate use of individualized PSA testing and mass, population-based screening, and the relative merits of the former compared to the latter. They both seem to agree that “Change is clearly in order,” and that “A complete cultural overhaul is needed to change the perception that all prostate cancer needs to be treated.” That change in perception needs to include clinicians and patients, according to Dr. Thrasher.

This is something that The “New” Prostate Cancer InfoLink would entirely endorse. We have trivialized the PSA test, giving it a power that it does not have, and then living with the overtreatment of prostate cancer as a consequence.

“You wouldn’t just decide on the spot to do a mammogram,” said Dr. Stark, explaining that such quick decisions are common with PSA testing. “Somehow, we have to approach screening for prostate cancer with the same prudence we would have in screening for breast cancer or colon cancer,” she added.

The bottom line to all of this is that men and their doctors need to spend a lot more time discussing the pros and cons of PSA testing for each individual patient. Unfortunately, in the words of Woolf and Krist, in an editorial in the September 28 issue of Archives of Internal Medicine, “Today’s practice environment presents few incentives or support tools for [primary care] clinicians and patients who prefer a discussion rather than simply marking a checkbox for PSA on a laboratory requisition form.” We absolutely have to find a way to change that mindset so that some men are no longer rushed down to the lab for an unnecessary or an inappropriate test while others who have risk indicators do get sent for the PSA test — but with a good understanding up front of the potential consequences of a positive result to that test.

6 Responses

  1. It pains me how many of my referring physicians blindly draw PSAs on their patients, some well into their 80s and NEVER discuss CaP screening with those men. They are sent to me for an Informed Consent on screening that they didn’t know they were getting!

    I struggle for the words to use in my consultation report … “Thank you for sending this 85-year-old man who you have been screening for CaP and whose PSA is 4.3 ng.mL …”

    What a dreadful waste of our health care dollars!

  2. Dear Dr. Kelly:

    Thank you for this comment, which is helpful in endorsing the view of The “New” Prostate Cancer InfoLink that we have a long, long way to go before we can have a rational appreciation of what is driving so much of the misunderstanding and misapplication of PSA testing.

  3. It is a pity that most of your readers will not be able to access the excellent Catalyst program on Australian ABC which presents this approach in a very sensible, non-alarmist way.

    Perhaps at long last the ground swell that has been building for some years now about over-treatment will create some good waves. :-)

  4. According to an article in The Australian on Saturday, it would seem that there is going to be a VERY intense debate in Oz about the value of early PSA testing, with the Urological Society of Australia and New Zealand pitted against the primary care and the epidemiology community.

    This discussion appears to reflect almost exactly the debate ongoing in the USA.

    The “New” Prostate Cancer InfoLink would again emphasize its agreement with the idea that we need “A complete cultural overhaul” that addresses the entire way in which we think about testing for risk of, diagnosis of, and management of prostate cancer. We are over-treating this disorder, and we are not giving men the very best possible guidance about their clinical risks.

  5. My father and all 3 uncles had prostate cancer. Four years ago my GP was cutting back prior to retirement and had me find another doctor for my yearly physical. I informed this guy of my history and he ordered blood tests, all of which were normal except for a somewhat low testosterone. It never occurred to me that no PSA was measured.

    A few years go by and I develop a prostate infection, for which I see my long-time doctor (who is still working 3 days a week) and he says, “Go get your last few years of PSA tests.” Amazingly, there were none. Long-time doctor orders the test (5.2 ng/ml) and voila, I have surgery and stage T3a cancer at 55. Incredible stupidity by “new” doctor. My father and one uncle had doctors that caught their prostate cancer in time; they were cured. My other uncles died horribly. What else needs to be said?

  6. Seems that Joe was caught in the screening debate. There are many doctors who do not believe in early detection for prostate cancer. In recommendations by some organizations there is no mention of risk factors and they say that if a man asks for early detection tests, then a doctor must give them. If they don’t ask, then … This is not the first time I have heard a story like this.

    VPCC tells men to go to a doctor regularly and to ask his doctor about his need for screening. We seem to need more public messages like this.

    Spoke to a family practitioner last week who felt that because of the unknowns it was irresponsible to not do the test. If MD’s can’t agree, what are the poor patients going to do?

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