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Monday, January 28, 2019

Did a third randomized trial for PSA screening reconcile the conflict betwen the first two?

Did the third RCT settle the issue of the efficacy of PSA screening for prostate disease?  The short answer is no - that settling purportedly was   achieved by another statistical analysis. ( see reference # 2 for that) at least for a while .

There are now three large RCTs (1) that have addressed the subject.

1) the PLCO
2) The ERSPC
3) the Cluster Randomized Trial of PSA testing for Prostate Cancer.

Only the ERSPC demonstrated reduction in cancer in an "invitation to screening"  with PSA setting.

So did the two out three being negative settle the issue? Not even close.

In 2012, faced with two conflicting RCTs the USPSTF decided to recommend against screening with PSA.Then a third RCT was completed showing no difference in mortality in the PSA screened group.

So if the score was 2 to 1 showing no benefit for PSA screening why did the USPSTF recant and return to their recommendation of "shared decision making" in 2018?

 The answer seems to be that Tsodikov from the University of Michigan ( and 21 other authors from various institutions)   did some adroit statistical footwork (2) in an effort to reconcile the disparate findings. Their work appears successful with the conclusion
being that when the proper type analysis is done (taking into account mean lead time) both the PLCO and the ERSPC both demonstrated approximately the same decrease in mortality with PSA screening.
Note the original analysis did not show a benefit to screening .

So now the score is two RCTs in favor of screening with one against and the current USPSTF recommendation is for shared decision making.

1)A blueprint for cancer screening and early detection :Advanced screening's contribution to cancer control. Wender RC et al . Ca,A Cancer Journal for Clinicians, Vol 49, no 1 Jan/Feb 2019 ( This is an excellent review of screening for cancer detection in average risk, asymptomatic adults including breast,cervix,colorectal,endometrial,lung and prostate.

2)Tsodikov, A Reconciling the effects of screening on prostate cancer mortrality in the ERSPC and PLCO trials, An Intern Med. 2018, 168 608

"Life is short,art long,opportunity fleeting, experience treacherous,judgment difficult."Hippocrates.

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