European men overestimate the potential benefit of prostate cancer screening …


… and we suspect that a similar study, if carried out in the USA, would come to similar conclusions.

Gigerenzer et al. carried out a careful and detailed study in 9 European countries in an attempt to obtain accurate, country-specific information on public knowledge of the benefits of screeningfor breast and prostate cancers. Their study was based on face-to-face, computer-assisted, personal interviews with 10,228 persons in Austria, France, Germany, Italy, the Netherlands, Poland, Russia, Spain, and the United Kingdom. Their goal was to assess perceptions of cancer-specific mortality reduction associated with mammography and PSA screening. Participants were also queried on the extent to which they consulted 14 different sources of health information.

Based on the currently available data, in which “screening” is defined as mass, population-based screening of large numbers of people within a well-defined population (and taking account of the recent data from screening studies such as the PLCO and ERSPC trials, the authors began from the position that:

  • 1 life is saved among each 1,000 women screened for breast cancer using mammograms.
  • 0 or 1 life is saved among each 1,000 men screened for prostate cancer using the PSA test.

One may want to argue about these assumptions, but those were the assumptions which the authors used in constructing this specific study.

Based on these assumptions, their study demonstrated that:

  • 92 percent of women overestimated the mortality reduction from mammography screening by at least one order of magnitude or reported that they did not know.
  • 89 percent of men overestimated the benefits of PSA screening by a similar extent or did not know.
  • Women and men aged 50–69 years, and therefore targeted by screening programs, were not substantially better informed about the benefits of mammography and PSA screening, respectively, than men and women overall.
  • Frequent consulting of physicians and health pamphlets tended to increase rather than reduce overestimation.

The authors concluded that, “The vast majority of citizens in nine European countries systematically overestimate the benefits of mammography and PSA screening,” and that “In the countries investigated, physicians and other information sources appear to have little impact on improving citizens’ perceptions of these benefits.”

Now let’s be very clear what these results mean.

The question that each male participant in the survey was asked was, “1,000 men age 50 and older from the general population participate every 2 years in screening for prostate cancer with PSA tests. After 10 years, the benefit is measured. Please estimate how many fewer men die from prostate cancer in the group who participate in screening compared to men who do not participate in screening.”

The possible answers (out of 1,000) were: 0, 1, 10, 50, 100, 200, and “I don’t know.”

Here are the actual average results across all 9 nations:

  • 8.3 percent of men answered 0 and 2.4 percent of men answered 1; so 10.7 percent in total gave a “correct” answer of 0-1 in a thousand.
  • 14.4 percent of man answered that 10 lives would be saved.
  • 19.3 percent of men answered that 50 lives would be saved.
  • 14.0 percent of men thought that 100 lives would be saved
  • 11.8 percent of men thought that 200 lives would be saved
  • 29.8 percent of men said they didn’t know.

These data imply that 59.5 percent of the men questioned believe that 10 or more lives are saved for each 1,000 men who are screened for prostate cancer, and there are absolutely no data to support such a belief. Why do we believe this?

We believe this because it is part of the justification that we make to convince ourselves individually that our treatment of our prostate cancer will help or has helped to save our life. And many in the physician community are complicit in helping us to reach this conclusion because it is in their interests to treat us.

However, the majority of men who are getting tested for and diagnosed with localized prostate cancer today really do need to appreciate that their life is in minimal danger. In other words, for the majority of the newly diagnosed, it is not primarily about mortality. What is in much more danger is their quality of life if they have progressive prostate cancer, because of the need for escalating forms of treatment up through radiation, hormone therapy, and chemotherapy, and all of the associated complications of these therapies.

10 Responses

  1. The results of the study that indicate that for men diagnosed today with localized prostate cancer face a minimal danger is in contradiction with the natural history of prostate cancer as represented by data from Scandinavia. Why is this data ignored?

    In a retrospective study by Damber and Grönberg, 6,890 patients with prostate cancer from the North Swedish Cancer Register were analyzed according to cancer-specific survival. Prostate cancer mortality was 40% in patients with well differentiated cancers, 54% in patients with moderate differentiated prostate cancer and 72% in men with low differentiated prostate cancer. Prostate cancer mortality was 80% in men younger than 60 years, 63% in men 60-69 years old, 53% in men 70-79 years old and 49% in men older than 80 years.

  2. Dear Ralph:

    I would respectfully point out that the study you reference was based on men diagnosed largely in the 1980s, and most of these men would have been diagnosed because they already had symptoms suggesting clinically significant prostate cancer, not on the basis of a PSA test. In other words, the high mortality rate in this study occurred because these were the men at high risk for clinically significant disease, regardless of their Gleason score.(The PSA test did not become widely used to test for prostate cancer risk in Sweden until at best the late 1980s.)

    These men are in no way representative of the average man being diagnosed in North America today.

    No one is suggesting that men don’t die of prostate cancer, but we will never overcome the problem of scaring people into unnecessary treatment until we are clearly able to get people to understand what their real personal risk is for: (a) prostate cancer-specific death; (b) progressive prostate cancer and the complications thereof (even if they don’t die of the disease); (c) histologically evident but not clinically significant disease that can be monitored in an appropriate manner until it becomes apparent that treatment is necessary; and (d) the complications of treatment that may never have been necessary in the first place.

    As far as I am aware, in North America today, somewhat less than 3% of men who are actually diagnosed with prostate cancer die of this clinical condition. That means that 97% of those who do get diagnosed die of something else.

  3. Mike: I do not deny the fact that those men do not represent men diagnosed today. They do represent the natural history of untreated prostate cancer when there is no marker like PSA to detect earlier stages of the disease. Also note that 40% had well-differentiated cancers at diagnosis. Let’s not talk of the 97% that get diagnosed and die of cardiovascular disease. Let’s talk about the 3% that die of prostate cancer — and many unnecessarily. Obviously even now the disease is not as indolent as claimed.

    If “screening” with PSA is inferior and somehow ruled illegal, wouldn’t we regress back to the same situation these men faced? Is the mortality reported by this study insignificant? The key is that through screening with the marker we presently have (PSA) to identify those that need treatment and those that do not. This is not as precise to totally avoid overtreatment, but at least will minimize the situation.

    What about scaring men to be tested? What is wrong with being tested and then having guidelines for practitioners to follow. I am supportive of active surveillance, but I can resist fighting back those that send mixed signals to an apathetic population of men that continues to die while diagnosed with advanced disease. Why aren’t these cases highlighted as such?

    Funnily, breast cancer seems to be in the same situation, but we will never see this expressed in the same terms as prostate cancer.

  4. Ralph: I entirely sympathize with your desire to ensure that all men who are indeed at risk of dying from prostate cancer are diagnosed and treated with curative intent long before their cancer “goes nuclear.” Conversely, however, I also hear and understand the concerns of those who worry about the potential for overtreatment of the 97% of men who receive a diagnosis of prostate cancer but are destined not to die from their cancer. It is not a question of one or the other. It is imperative that we address and educate people about both types of risk.

    With respect to the fact that breast cancer seems to have the same issues but is discussed in different terms, I refer you to the wise words of our friend Arthur (of Ask Arthur fame — or infamy). Earlier this morning, in answer to a reader’s comment/question, he stated:

    “Arthur says that there is a fundamental difference between breasts and prostates: the former are evident and of vast (if misplaced) cultural significance; the latter are not. This drives a great deal of the relevant behavior.”

  5. The problem I have is that the message given tells men: you will not likely die of prostate cancer (and if you do remember you are in the minority)…

    Yes and tell Arthur, breasts are attached to females that have more of what it takes to push back…

  6. Ralph:

    Luv ya as I do … The message you are hearing and the message others are trying to send are not necessarily the same thing. We are all biased by our perceptions.

  7. Mike, I accept that. I am biased because I know that without a PSA test I would been dead a long time ago. What message are they trying to send when they recommend that 75-year-old men do not need to be tested?

  8. Ah … Different issue. Absolutism is the enemy of reality. I would argue that there many 75-year-olds for whom PSA testing is a total waste of time … and there are some for whom it is utterly appropriate, which is why we have consistently backed the findings of the Iowa Prostate Cancer Consensus — from the day that they were published.

  9. Not quite a different issue because the reality is that the use of PSA is being questionned at any age because of the issue of over-treatment and the fact that “only” 3% of men die from prostate cancer. This in spite of being the second cause of cancer mortality in men …

    What the heck, why worry when we don’t even have a Government Office of Men’s Health …

  10. “only 3% of men die from prostate cancer.”

    Those 3% have names.

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