In October, 2011, when the US Preventive Services Task Force issued a draft recommendation against the use of PSA-based screening for prostate cancer, I wrote a LIVESTRONG blog about what the debate meant for men. This week, the Task Force published its final recommendation statement, after reviewing many public comments, and has continued to recommend against PSA-based screening for prostate cancer among men of any age.
In addition to my comments last October, I’d like to share a few more observations. I admit, this blog is long. But this issue is complex. And if you don’t trust the independent experts from the Task Force who recommend the end of mass PSA screening and you want to make an your own personal decision, you need to process a lot of information to make an informed choice. Your physician will not have the time to review all of this with you in a visit. (And, as an aside, they will not be paid to spend that time, as opposed to just ordering a test.) So if this is important to you, take some time now.
“Never question another man’s motive. His wisdom, yes, but not his motives.”
First, as you listen to the debates and make decisions for yourself about the merits of PSA-based screening tests, it is important to look beyond the rhetoric and examine the facts. Both sides of the screening argument should be assumed to have the best interest of men’s health at heart. Those for and those against the routine use of PSA screening all agree that prostate cancer is very common: autopsy studies show 1/3 of men aged 40-60, and 3/4 men over age 85 have prostate cancer. Prostate cancer, in some of those men, can advance to cause very significant problems including urinary obstruction, bone pain or pathologic fractures, and, in over 30,000 men last year, death. We all want to reduce the serious problems of prostate cancer, and the debate is not advanced by focusing on the motives of those on each side of the argument. The Task Force is not “big government rationing health care,” but an independent, voluntary body, whose potential conflicts of interest are openly disclosed and who are selected on the basis of expertise in preventative medicine. Likewise, published critics of the Task Force’s recommendation are not driven by greed to maintain the “lucrative business” of mass screening, but sincere physicians who work in primary care, urology, and oncology to care for men who suffer from the problems of prostate cancer.
“Tissue is the issue.”
Second, PSA tests (alone or combined with rectal exam or ultrasound) do not make the diagnosis of prostate cancer. Only a biopsy can do that. The debate at hand is about mass screening of the asymptomatic, general population to find those at high risk to have a silent case of prostate cancer, and should consider going on to a diagnostic biopsy. The question at hand is not about whether to use PSA testing or other means to decide which men who actually have signs or symptoms (like trouble urinating or pelvic pain) need to move on to a biopsy: that is the process of making a diagnosis for troublesome signs or symptoms. This controversy is only about whether men without any signs or symptoms and with average risk for the disease should be screened.
“Keep your eyes on the prize.”
Third, it is important to first consider what should be the ultimate goal of medical care directed towards prostate cancer. This might seem, at first, to be an obvious prize: the goal is to improve survival. But in fact, the goals are much, much more complicated. Consider overall mortality (death, from any cause including the prostate cancer) versus prostate cancer-specific mortality (death that is attributed to the prostate cancer itself, not a car wreck, heart attack, or other cause). An effective screening test for prostate should be expected to lower mortality due to prostate cancer, not car wrecks or heart attacks, and prostate-cancer specific mortality is the endpoint that the major studies under analysis considered. Since the overall mortality rate is not improved with PSA-based screening, we get into a more complicated area of which kind of death is better or worse (prostate cancer with severe bone pain or other problems versus dying of something else) and at what cost (living life with complications of the prostate cancer treatment such as erectile dysfunction, incontinence, hot flashes or bowel problems). Now we get into the art of medicine, and the real role of personal, informed choices.
But back to the science for a moment. The Task Force, and their critics, focused on the facts around whether or not the benefits of PSA-based screening (as measured by death from prostate cancer) are worth the harms (complications from biopsies, and substantial rates of complications from treatment of men who would otherwise not know they even had prostate cancer and would ultimately die of something else). This might also seem to be easy: just follow a large number of men, some who get PSA-based screening and others who don’t, and record what happens. But the design and execution of high-quality, scientific studies to get to these facts has not been easy. Some examples of the issues in the studies cited by both the Task Force and their critics include who was enrolled (general population versus those at some increased risk: one study included 40% in the no PSA group who had actually had a PSA test within 3 years of the start of the trial). Studies used a variety of “PSA-based” screening tests (PSA alone or with rectal exam or ultrasound, PSA testing frequency ranging from annual to every 7 years, cut-off for a “positive” test ranging from 2.5 to 4.0 to 10.0 micrograms/L, tests of free PSA, or measurements of PSA velocity over time). Keep in mind that changing the definition of a positive test from 2.5 to 4.0 reduces the number of “positive” tests in half, and from 4.0 to 10.0 reduces the positives again (from 1,200,000 to 352,000 in the US). Men with “positive” tests may undergo different biopsy techniques with different success rates of establishing a diagnosis. And among those men diagnosed with prostate cancer, there is a very big range of treatments they may pursue (observation, surgery, radiation, hormone therapy, or combinations), each of which may have a different effect on both side effects and survival. Finally, studies all report overall survival, and that is straight-forward. But among many elderly men with multiple medical problems, it can actually be difficult to assign a cause of death as prostate cancer, when even a man is known to have advanced cancer. Many studies do not extensively report other important outcomes such as side effects of biopsies and treatments, quality of life, or levels of function. Hence, well meaning experts across the spectrum of this controversy will find areas to critique.
“A personal choice”
The real purpose of PSA testing (or any screening test) is gather additional information about your risk for an undiagnosed disease. Aside from the small cost, a blood test has very little real risks in and of itself. The real question is, what will you do with that additional information? It turns out that most men with abnormal screening do go on to pursue a diagnostic biopsy (which does come with some greater risks for harm). And of those who receive a diagnosis of prostate cancer, 60-90% choose active therapy with surgery, radiation, hormones, or combinations (with even greater risks for harm).
As I said this is a complex personal choice. What would you do at each step? An informed choice includes considering each of those decision points. If you question the Task Force recommendation, read the report. Then read the two opposing commentaries.
“The bottom line”
From the Task Force report: “All but 1 randomized trial has failed to demonstrate a reduction in prostate cancer deaths with the use of the PSA test, and several—including the PLCO trial—have suggested an increased risk in screened me, potentially due to harms associated with overdiagnosis and overtreatment.” And PSA testing in the US “presupposes that most asymptomatic prostate cancer cases will ultimately become clinically important and lead to poor health outcomes and that early treatment effectively reduces prostate cancer-specific and overall mortality. However, long-term, population-based cohort studies and randomized treatment trials of conservatively managed men with localized prostate cancer do not support this hypothesis.”
The bottom line is this. While the PSA test has many other good uses, it is not good enough at detecting who has hidden prostate cancer of the sort that is going to become aggressive and cause major problems or death. And the current treatments for prostate cancer have too many side effects and do not effectively cure enough men to be used broadly among those whose prostate cancer is not destined to cause major problems or death. Both of those issues must change, and our energy must be focused on the research needed to develop better screening tests and better prostate cancer treatments.
In the meantime, I believe that the time for routine use of PSA-based screening for prostate cancer among the general US population has ended.