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Us TOO FLORENCE - BEHIND THE HEADLINES-7 BY BOB HORNEY - PROSTATE CANCER SURVIVOR - Us TOO CHAPTER LEADER (Published March 12, 2014, The Siuslaw News) In 2012, the U.S. Preventive Services Task Force (USPSTF), based on data from two prospective, randomized trials, recommended that healthy men of all ages no longer receive the PSA screening test for prostate cancer. Further, the USPSTF says there is little, if any, evidence that PSA testing saves lives and that too many men instead suffer from impotence, incontinence, heart attacks and occasionally death from treatment of tiny tumors that would never kill them. In coming to its "no PSA screening for healthy men" decision, the USPSTF relied most heavily on the results of the Prostate, Lung, Colorectal and Ovarian (PLCO) Trial, a product of our National Cancer Institute (NCI). The PLCO was supposedly designed to tell us if annual PSA and DRE tests reduced prostate cancer deaths. Here's how Dr. Otis Brawley, Chief Medical Officer of the American Cancer Society, describes such a screening trial: "It is a prospective randomized trial of a group screened compared with a group not screened in order to look at death rates in the two groups over time." As per his description, men were recruited and those who met established criteria were randomly assigned to one of two groups - one that would be given PSA and DRE tests as part of the trial (the screened group) and one that did not get those tests as part of the trial (the control group). After some years, the deaths from prostate cancer in the two groups would be compared. That comparison, screening versus no screening, would reveal if deaths from prostate cancer were reduced due to annual PSA and DRE screening. As you read on, you'll see that the NCI authors had a different design in mind...a trial that permitted participants in the control group to get (on their own) all the PSA and DRE tests they wanted during the trial. The PLCO trial didn't have a true control group. The control group was listed as a "usual care" group, meaning the men could do as they pleased - get PSA tests or not. In other prostate cancer trials to see if PSA testing reduced deaths due to prostate cancer, all of those PSA tests in the usual care/control group were considered "contamination" and affected the results - negatively. They shouldn't happen. By permitting those tests into the trial, the NCI rendered the trial useless for the information the USPSTF was seeking. There's no question that over 40 percent of the men in the usual care group entered the trial with a prior PSA test. It is also widely accepted that at least 52 percent of the usual care group had received a PSA screening by year 6 of the trial. Some analysists say that number eventually rose to around 80 percent. It is a fact that only 85 percent of the participants in the screened group actually underwent screening. When questioned about so many men in the control group being screened, Dr. Virginia Moyer, Pediatrician and the task force chair responded thusly: "The study has a known flaw - that a fair number in the control group got screened - which would tend to make the intervention and control groups look more alike." To which she added, "The task force, however, offset this potential bias with the inclusion of the European study. The different methodologies used in the two studies provided balance." We'll look at the European study later. I have to question Dr. Moyer's "fair number" getting screened. It seems like a self-serving understatement which belies the true extent of testing in the usual care group. I also question using the European study (or any study) to balance the "potential bias" in the flawed PLCO. Neither she nor the entire USPSTF can simply "decontaminate" the PLCO with different methodologies...or wishful thinking. |
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