28-year risk for prostate cancer in Copenhagen based on baseline PSA data

Between 1981 and 1983 researchers collected and stored blood samples from 4,500 men in Copenhagen, Denmark, as part of the Copenhagen City Heart Study. These blood samples had been carefully stored — and otherwise unused — for nearly 30 years. In 2010, a new research team decided to measure the PSA levels in these blood samples.

The research team was then able to correlate these 28-year-old PSA data with data from the Danish Health Registries to identify which of the blood donors had subsequently been diagnosed with or died of prostate cancer between 1983 and 2010.

Their findings appear to suggest a correlation between baseline PSA level, risk for prostate cancer diagnosis, and risk for prostate cancer-specific mortality — according to a report by Sussman on MedPage Today.

After stratifying the men into six groups based on their PSA levels, Orsted and his colleagues were able to show that:

  • Among men with a baseline PSA of < 2 ng/ml in 1981-83, 90 percent were free of prostate cancer 30 years later (inclusive of men in their 90s).
  • Among men with a baseline PSA of ≥ 10 ng/ml in 1981-83, 75 percent had developed prostate cancer by the time they were 80 years of age.
  • Elevated baseline PSA levels correlated with an  increased risk of prostate cancer depending on the baseline level of PSA (between three and 44 times the risk of those with a baseline PSA of < 2 ng/ml).
  • Elevated baseline PSA levels correlated with an 2-fold-to-12-fold increased risk of prostate cancer-specific mortality (between two and 12 times the risk of those with a baseline PSA of < 2 ng/ml).

Quoted in discussing these results, Dr. Orsted said that,

This study supports the idea that a baseline test is maybe a good idea. It suggests that in men 40-45 years of age we can use a first measurement of PSA as a way to move forward.

He also stated that:

For the large majority — more than 90 percent of men — there was a very low 10-year risk. This finding can be used to reassure these men and may reduce some of the major problems in prostate cancer — over-diagnosis or too many PSA tests with also unnecessary prostate biopsies.

This is yet another study presented at the European Multidisciplinary Cancer Conference (EMCC) over the weekend.

The data from this study appear to be supportive of data previously published by Lilja, Vickers, and others based on Swedish patients. As with the Swedish data, they appear to offer a rationale for much less frequent PSA testing among men with a low baseline PSA level unless PSA testing is suggested by other clinical events.

5 Responses

  1. This might be interesting data but I am not sure how it relates to the many instances of men with PSA levels between 2 and 10 ng/ml. I know of four men in my age group that have been diagnosed with prostate cancer who had PSA levels much less than 10 ng/mL. I don’t see how these data are very useful except to reassure men with very low PSA concentrations.

  2. Dear Jack:

    That is the entire point of this study. It is about the potential importance of a low baseline PSA level for men in their 40s. Such men probably don’t need annual PSA testing. Men with PSA levels between 2 and 10 ng/ml are at significantly higher risk and need much closer monitoring.

  3. What is critical and not clear is the age of the 4,500 men tested; it is not clear to me they were all in their forties. The more diverse the ages, the less reliable the conclusions.

  4. Rick: I am reasonably sure that if you get the full text of the paper by e-mailing the authors, it will give you a detailed age breakdown of the patients. If they were followed for up to 30 years, and some were in their 90s at the time of follow-up, then it seems likely that the age range of the patients was between 35 and 60 at the time that the blood was drawn, but the PSA level still offers a “baseline” for the PSA level of each individual patient regardless of that patient’s age, because they had never previously had a PSA test.

  5. Couple of further observations on these results:

    (1) There is a rule-of-thumb (although I have never seen the studies) that the percentage of men with prostate cancer in any age cohort corresponds to their decade — for example, some 30% of men in their 30s have prostate cancer, 40% in their 40s, 50% in their 50s etc. Identifying 75% of men at age 80 is pretty consistent with that premise.

    (2) There is a huge caveat in drawing any conclusions without knowing the age distribution of the original group. For example if the age group back in the early 80s was roughly 35-60 and biased to older men, then we would expect there to be a much higher disease-free ratio; PSA increases with age and older men with a baseline PSA < 2 display lower risk than younger men with a baseline PSA < 2.

    Doubt I will follow up to get a copy of the paper. My comment is just that we should include the caveat that we should consider their conclusions recognizing we need to know the age distribution of the sample.

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