THE "NEW" PROSTATE CANCER INFOLINK

A new update on the prostate cancer outcomes of the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial has given us a rather different interpretation of the meaning of the data from this trial — although whether that “meaning” actually has “meaning” is probably up for debate.

In the new paper by Pinsky et al. (just published on-line in the journal Cancer), the authors now argue that the data from this trial show that, at 15 years of follow-up:

• There was still no reduction in prostate cancer mortality for the intervention arm versus the control arm.
• There was no reduction in overall mortality for the intervention arm versus the control arm.
• Because of the high rate of PSA testing among the men in the control arm (who weren’t meant to get tested at all), the data can be interpreted to mean that there was “no benefit of organized screening versus opportunistic screening.”

What Pinsky et al. actually report from the latest analysis of the data is the following:

• Between 1993 and 2001, the trial enrolled 76,683 men who were at potential risk for prostate cancer (based solely on their ages).
• About half the men (n = 38,340) were randomized to the intervention or formal screening arm of the trial (in which they received PSA tests every year for 6 years and rectal exams for 4 years).
• The other half (n = 38,343) were randomized to a control arm, in which it was naively assumed they would have no form of testing for risk of prostate cancer unless they showed symptoms suggestive of a urologic problem.
• It is now estimated that, during the course of the screening phase of the trial,
  • 86 percent of the men in the control arm received at least one PSA test.
  • An average of 46 percent of the men in the control arm received a PSA test in any one year.
  • 99 percent of the men in the intervention arm received at least one PSA test
  • An average of 84 percent of men in the intervention arm received a PSA test in any one year .
• The median follow-up time as of the latest data analysis was 14.8 years in the intervention arm and 14.7 years in the control arm.
• There have been 499 deaths from prostate cancer to date in the study cohort.
  • 255 deaths from prostate cancer occurred in the intervention arm.
  • 244 deaths from prostate cancer occurred in the control arm.
• The prostate cancer-specific mortality rate ratio (RR) between the two arms is 1.04.
• The all-cause mortality RR between the two arms is 0.977.

So what we have discovered from this trial after 23 years of study is that a formal, regular process of screening with regular PSA tests and rectal exams had no impact on either prostate cancer-specific or overall mortality rates as compared to an informal process of individual testing with the PSA test (and maybe rectal exams too).

Should we be surprised by this? Well, not in the opinion of your sitemaster … but his is just one opinion.

The real question remains: Does a formal process of screening men for prostate cancer over time have any impact on overall or prostate cancer-specific mortality as compared to no testing at all. The data from the Göteborg study suggests that it does. And it is only the data from the Göteborg study (when included in the compiled meta-data from the European Randomized Screening for Prostate Cancer or ESRPC study) that drives the data from the ERSPC indicating a prostate cancer-specific mortality benefit from screening. Your sitemaster is optimistic that the ongoing, randomized trial in the UK, which has involved way more than 75,000 men, may be able to finally resolve this issue one way or the other.

Filed under: Diagnosis, Management, Risk | Tagged: benefit, mortality, risk, screening, testing |