In a recent paper published in Urology author Paul Alpert, MD discusses his work, “New Evidence for the Benefit of PSA Screening: Data From 400,887 Kaiser Permanente Patients.” The study objective was to investigate whether prostate cancer screening with PSA is beneficial in reducing prostate cancer mortality, and to determine optimal screening intervals and age groups to be screened.
QUESTION: Dr. Alpert, you’ve had a long-standing affiliation with UCSF, would you describe this as a collaborative study?
ANSWER: I think we can describe this as a collaborative study, as I began it when I was a practicing urologic surgeon at Kaiser Permanente, and completed it while working as a research physician at UCSF. The data is exclusively from Kaiser-Permanente Northern California patients, and so it represents an average population of subjects from the community, rather than a population skewed by subjects referred to a tertiary care center.
QUESTION: This paper is being released just as the United States Preventive Services Task Force (USPSTF) revised its recommendation on prostate cancer screening from a “grade D” to a “grade C.” Can you help our readers understand why there is a controversy about whether or not a man should be screened?
ANSWER: PSA screening for prostate cancer has been controversial since the PSA test was first licensed by the FDA in 1986. It was hoped that through early detection, death from prostate cancer could be substantially reduced. But after 30 years, evidence for its usefulness has been questioned. In May 2012 the US Preventative Services Task Force downgraded their recommendation, advising against PSA screening in healthy men, concluding that PSA screening causes overtreatment and that the modest benefits of screening are outweighed by the harms.
QUESTION: Why would the USPSTF make this kind of determination?
ANSWER: There have been two major problems. The first is that the only good study on PSA testing, the European randomized Study of Prostate Cancer (ERSPC) used 4 year screening intervals, and found only a 21% decrease in prostate cancer deaths with screening, a significant, but modest benefit. In addition, the ERSPC showed no change in all-cause mortality, leading to the assertion that while cancer deaths were being decreased, overall longevity was not being improved, as patients were just dying of other causes. The second major problem is that indeed many patients with low grade prostate cancer were unnecessarily treated in the early years of PSA testing. Recent evidence shows that about 25% of patients newly diagnosed with prostate cancer have a non-aggressive cancer that will never progress, and these subjects do not need treatment, and in fact if treated, have all the downsides of treatment with no benefit.
In the last 15 years, we have been able to address this second problem with Active Surveillance, a process in which we identify the roughly 36% of subjects with cancers least likely to progress, and with careful follow-up, treat only the 11% who have evidence of progression over the next few years, and are then able to leave untreated the 25% who will never require treatment.
QUESTION: What does your study tell us about screening?
ANSWER: Our current study addresses the first major problem, that of only modest benefits to screening. This study looked at more than 400,000 patients who had PSA testing done at Kaiser Permanent Northern California in the years 1998 through 2002. This was the first study to look at various screening intervals, and at various age groups being tested. We had enough subjects so that we were able to look at 6 different screening intervals and at 7 different age groups. This data showed that 1-year screening is the most effective screening interval, and that men aged 55-74 have the greatest benefit from screening with a 64% decrease in cancer specific death rates. So the benefits are no longer so modest. And in addition, there was a 24% decrease in all-cause deaths for this group at 12-16 years of follow-up, when compared to no screening. So this is also the first study to show an all-cause mortality benefit for PSA screening, and negates the argument that overall longevity is not being improved.