Response to USPSTF Prostate Cancer Screening Recommendation
Simon J. Hall, MD, Director of Deane Prostate Health and Research Center, explains why he believes the recommendations of the U.S. Preventive Services Task Force regarding the prostate-specific antigen (PSA) test for prostate cancer are misguided.
A recent report from the US Preventive Services Task Force (USPSTF), a congressionally mandated panel composed of primary care providers, recommended against PSA-based prostate cancer screening. This has resulted in a significant amount of media attention and confusion for both patients and physicians. The Task Force came to their conclusion following a review of the literature, essentially focusing on three studies contrasting, in their opinion, the lack of evidence that screening and treatment actually improve survival with the negative impact treatment can have on urinary and sexual function. While I would agree that some aspects of their report are correct, to turn the clock back to the 1980s, when the only screening test for prostate cancer was a digital rectal exam, is the wrong final conclusion and recommendation.
The first study analyzed was the US Prostate Lung Colorectal and Ovarian Cancer screening trial, published in the New England Journal of Medicine in 2009, which concluded PSA screening did not result in reduced prostate cancer deaths. However, this study reported seven-year follow-up, which is not sufficient time to analyze for prostate cancer deaths due to its relative slow progression in non-treated patients. Additionally, almost half of the men in the non-screened arm had a prior PSA. In my opinion, this central flaw invalidates any conclusion of the study. Further, I believe it was only published in the same volume of the New England Journal of Medicine as a much larger European study with ten-year follow-up for political reasons and not based on the legitimacy of its content. The European study compared screening with standard diagnosis demonstrated a 20 percent reduction in mortality from prostate cancer in screened men. The Task Force pointed out that many men were over-treated, to the order of 46 men for every man saved. But the investigators believe that with 15-year follow-up this number will narrow to somewhere between 1 of 15 men to 1 of 20. However, little information about the age of the men and the aggressiveness of the cancer is reviewed, which is important in interpreting the results. I believe that with maturity this study will give us a better handle on when to stop screening and how aggressively to treat based on the biologic significance or aggressiveness of an individual’s cancer matched with his age.
The age factor was analyzed by the third quoted study, which evaluated radical prostatectomy versus no treatment in a group of men from Sweden. The study demonstrated that with 13-year follow-up there was indeed a significant difference in mortality in favor of surgery, but only for men who were aged 65 or younger at diagnosis. However, this study was restricted to men with only well-differentiated cancers that were palpable and thus not PSA-detected. This study may not correlate with PSA-detected, more aggressive cancers (defined as those receiving Gleason grades of 7-10). A smaller study not discussed in the Task Force report was conducted in Sweden in younger men, in theirmid-50s, noting the number to treat to cure of 1 in 12, again underscoring the importance of bringing consideration of age into the screening debate.
This controversy centers on two issues. The first is the validity of the PSA blood test to detect prostate cancer. We know there is no PSA level that guarantees the absence of cancer. At the same time, most men with an elevated PSA do not have cancer. The PSA blood test should not be reviewed in a vacuum; rather it should be interpreted in the context of patient age, race (given that African-American men have a higher incidence of prostate cancer), family history and the size of the prostate. This type of comprehensive and personalized assessment is essential before making the decision to undergo a biopsy which is the only way to conclusively diagnose cancer. The second controversy centers on the evidence that definitive treatment of an asymptomatic patient with a non-palpable PSA-detected cancer results in a better outcome for a patient versus the outdated way of being diagnosed by an abnormal rectal exam or by accident at the time of a prostate surgical procedure. While I would agree that the evidence is not fully mature and detailed enough to make a definitive conclusion, it does point toward a more positive outcome for men who are treated versus those who are not. Prostate cancer is a heterogeneous disease, and many men do have low-volume, low-grade cancers, which, depending on each man’sage, may not need to be treated at all. One must balance this with the fact that over 30,000 men die from prostate cancer every year, usually from the more aggressive types of cancer. While the task force report focused on the side effects of treatment, specifically incontinence and impotency, it did not address the pain and suffering of patients with metastatic prostate cancer. This is important as many studies have documented that a major driver in the decreased mortality of prostate cancer in the United States is due to the marked reduction in the number of men who are diagnosed with metastatic disease at their initial presentation. If we turn the clock back to the pre-PSA era, this disease state will once again be experienced by a large cohort of American men.
I believe the USPSTF had the opportunity to produce a well thought out, evidence-based review of prostate cancer screening, but unfortunately, missed it. A more accurate evaluation of these intervention trials should focus on the outcomes of patients with more aggressive prostate cancer and not all diagnoses, and factor in a patient’s age. To conclude that PSA screening and treatment have no impact or little impact on cure represents a misguided interpretation and/or lack of insight to the nature of the disease and understanding of the natural history of prostate cancer. I believe that until we have further evidence, which should be coming to fruition within the next five years, men should be discussing their risk profiles and screening guidelines with a urologist and interpreting their PSA within the context of that profile. Only then can a rational decision be made with respect to biopsy and treatment recommendations.