PSA testing has reduced risk for diagnosis with metastatic prostate ...

A paper published earlier today in Cancer has made a very reasonable attempt to estimate how many men would be being diagnosed annually today with metastatic (TxNxM1) prostate cancer if there was no PSA test and the rates of diagnosis were the same as they were back in the late 1980s ? before PSA testing was widely available.

The bottom line to this paper by Scosyrev et al. is a prediction that, in the complete absence of PSA testing for risk of prostate cancer, we would have seen about 25,000 new cases of men being initially diagnosed with metastatic disease in 2008 as opposed to the estimated 8,000 actual cases. In other words, the availability of PSA testing has cut the risk of an initial diagnosis of metastatic prostate cancer by a factor of about 3.1.

However, it should also be pointed out that the risk for a diagnosis with metastatic prostate cancer was shown to be highly dependent on both age and race. Just to give some examples, the authors project the following:

• There would have been no change at all in risk for a diagnosis of M1 disease in men of 40-49 years of age, regardless of race.
• Black males were (and are) twice as likely to be diagnosed initially with M1 disease as White males.
• Among White males aged 65-69 years the risk for a diagnosis of M1 disease would be increased by a factor of 3.5 if there was no PSA testing.
• Among Black males aged 65-69 years the risk for a diagnosis of M1 disease would be increased by a factor of 2.3 if there was no PSA testing.
• Among White males aged 75-79 years the risk for a diagnosis of M1 disease would be increased by a factor of 4.1 if there was no PSA testing.
• Among Black males aged 75-79 years the risk for a diagnosis of M1 disease would be increased by a factor of 5.8 if there was no PSA testing.

Now it needs to be made very clear that the authors are not suggesting that their data necessarily imply an association between mass, population-based PSA screening and the known decrease in prostate cancer mortality over the past 20 years. They are, however, pointing out that the use of PSA testing appears to have significantly reduced the risk of an initial diagnosis with metastatic disease. Their conclusions are hedged with all sorts of comments about issues such as lead-time effects and ?residual confounding?.

The authors are also very careful to note that the initial, rapid reduction in risk for a diagnosis with M1 disease occurred ?in the early and middle 1990s,? when there was still a large pool of men living (unknowingly) with asymptomatic or mildly symptomatic metastatic prostate cancer.

The key point that the authors make in their conclusion is the following:

? these estimates must be taken into consideration (bearing in mind the limitations of observational data) when public health policy-level recommendations are made regarding PSA screening.

This is a conclusion that The ?New? Prostate Cancer agrees with completely. However, we do not think that this conclusion necessarily implies that all men need annual PSA tests (mass, population-based ?screening?). What it implies is that we need to be realistic about the utility and value of the PSA test and base decisions about the use of this test on the data available about individual men and their personal risk for prostate cancer (in terms of things like age, race, and family history).

This is a valuable paper because it helps to provide context related to the value of the PSA test as a tool. We suspect that the data provided by this paper will, unfortunately, be misused by some to imply that annual PSA screening for all men of > 50 years of age continues to be essential. However, the authors are extremely careful to avoid any such statement, writing that:

These finding do not necessarily indicate that PSA screening of? men in their 40s is of minimal or no value in terms of preventing advanced stage at [prostate cancer] presentation

and

? we could not determine the extent to which screening of men in their late 70s contributed to the observed risk reduction in the age categories 80 to 84 years and ? 85 years

and most importantly

? we could not make specific recommendations regarding optimal cut-off ages at which screening should be started and stopped, nor could we investigate the optimal frequency of screening.

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Filed under: Diagnosis, Risk Tagged: | Diagnosis, M1, metastatic, PSA, race, risk, test

Source: http://prostatecancerinfolink.net/2012/07/30/psa-testing-has-reduced-risk-for-diagnosis-with-metastatic-prostate-cancer/

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