Analysis of PSA Screening Trials: More Clarity or Confusion?

Gerald Chodak, MD  


October 13, 2017

Hello. I'm Dr Gerald Chodak from Medscape. Today I want to talk about a new report that again addresses screening for prostate cancer. Tsodikov and colleagues[1] performed a mathematical analysis using the original data from both the Prostate, Lung, Colorectal, and Ovarian Cancer Screening (PLCO) trial and the European Randomized Study of Screening for Prostate Cancer (ERSPC) trial. They did a measurement called mean lead time. By showing that there was a similar mean lead time in both screening arms for the two trials, they are concluding that there was a similar impact in terms of reducing mortality from screening.

An editorial by Vickers[2] says that on the basis of this new report, the question about whether screening saves lives should be put to rest. We should instead focus on how to make screening more efficient and safe and reduce its harms. That would mean being more selective when performing a biopsy and not screening men over age 70. Most important, if low-risk cancer is diagnosed, then conservative therapy should be the primary way to start management.

The question, of course, is whether this new analysis puts to rest the question about whether screening saves lives. Unfortunately, there are some limitations. Substituting mean lead time for mortality benefit has potential biases. It is unclear from this analysis whether those were addressed.

Another major concern has to do with problems in the European trial that were not clearly discussed by many people, namely that it included seven different trials—five of which did not show a benefit, whereas two did. When Haines did his analysis,[3] they found some disparity in how men were managed. Men who had higher-risk cancers in the screened group were more likely to get aggressive therapy, whereas in the control group they were much more likely to get androgen deprivation therapy. Because we do not have clear proof that the two treatments are equal, this alone could have partly explained the difference in mortality that was observed in the Göteborg arm of the screening trial from Europe.

Where does that leave us? Does that still leave us with the question of whether screening saves lives, or does this new report put that to rest? I believe that we still have considerable uncertainty. This mathematical model does not prove a greater benefit from screening than the trials individually. It is not a substitute for showing a mortality benefit, which PLCO did not.

For now, we have to continue to counsel men that there is considerable uncertainty about the value of screening and explain to what extent they are likely to benefit or their odds of being overtreated. Hopefully, going forward, we can counsel men more effectively, which may not be being done at the present time.

I look forward to your comments. Thank you.


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