At the end of prostate cancer awareness month - a promotion driven in large part by those who push prostate cancer screening and treatments - this week's edition of the BMJ publishes a study, an analysis and an editorial all showing that there isn't enough evidence to support population-wide prostate screening with the PSA blood test. (Subscription required to access full text of all of these.)
Consistent themes in these publications:
• The PSA test cannot show the difference between cancers that will kill and those that are harmless, leading to overdiagnosis and overtreatment of healthy men.
• The PSA test doesn't produce the likelihood ratios (a measure used to predict disease) required for a screening test.• Other tests - other biomarkers for early detection of prostate cancer are needed before population based screening for prostate cancer should be introduced.
• Until a better screening test is available, men and their doctors should use a shared decision making approach to discuss the harms and benefits and the uncertainties of prostate cancer screening.
• One excerpt from a Harvard analysis:
"Given the current evidence, we support the opinion of the European Urological Association that data on costs and benefits remain insufficient to support population based screening. The financial and psychological costs of false positive results, overdiagnosis, and overtreatment of prostate cancer need to be measured more precisely. Better estimates of these costs should emerge from further evaluations of the large randomised trials.
Before testing men should be informed about the test itself and the interpretation of a positive or negative result. Moreover, they should be advised that the test cannot tell whether they have a life threatening cancer but that it could lead them through a thicket of tests and treatments that they might have better avoided. This advice follows the basic tenets of screening programmes laid out by the World Health Organization."
It seems to me that there are several overlapping debates going on when it comes to PSA testing -- public policy and individual decisions. If I understand what is going on, on the one hand there is the public policy question -- should universal PSA screening be instituted. I can see being opposed to that -- to essentially forcing men to get tested across all men and all medical practices. I think that the only men who should get PSA tests should be given rather detailed knowledge of the possible outcomes, options, followups, treatments, etc before being tested and possibly learning that they should have more testing, and then possibly learning that they have prostate cancer. Learning about these things after the fact is very difficult given the emotional state of a typical person who learns that he has cancer. On the other hand, when it comes to individuals, I think each of us should seek to acquire this information. What we need to learn is that, in spite of the potential pitfalls, PSA tests can lead to an improved quality and length of life if properly managed and avoiding PSA tests can lead to invasive prostate cancer. On the other hand we shouldn't have "universal screening" without "universal education" and more good drs but again as individuals we can acquire these things, in my opinion, and would be wise to seek to do so.
This is a complex issue. For additional perspective, I encourage you to check out stories I wrote about this in the May 15 and June 15, 2009 issues of Internal Medicine News www.internalmedicinenews.com. Also see www.auanet.org search psa09.pdf for guidelines from the American Urological Assn. Some say a process of active surveillance--measuring changes in risk over time--could help protect against overdetection and overtreatment.