New study attempts to resolve the PSA controversy
Since the 1990s, the prostate specific antigen (PSA) test has been used routinely to screen men for prostate cancer. However, last May the US Preventive Services Task Force (USPSTF) published a recommendation that “there is moderate certainty that the benefits of PSA-based screening do not outweigh the harms.” The USPSTF opinion sparked heated debate among the medical community. For example, the American Urological Association (AUA) promptly refuted the decision and asserted the benefits far outweighed the risks.
European researchers set out to resolve the controversy by offering a new approach to evaluating the benefits and harms of PSA testing, which they claim paves the way to a resolution of the controversy. They published their findings on August 16 in the New England Journal of Medicine.
The researchers noted that the units of measure are different for benefits (cancer deaths averted) compared with those for harms (overtreatment, erectile dysfunction, urinary problems). Thus, the researchers addressed the “apples-and-oranges problem” by using the same measure: quality-adjusted life-years (QALYs) to quantify the harms and benefits of screening.
The researchers noted that after 11 years of follow-up, the European Randomized Study of Screening for Prostate Cancer (ERSPC) reported a 29% reduction in prostate-cancer mortality among men who underwent screening for PSA levels. However, the extent to which harms to quality of life resulting from overdiagnosis and treatment counterbalance this benefit was unclear. They conducted a Microsimulation Screening Analysis (MISCAN) of the ERSPC follow-up data to predict the number of prostate cancers, treatments, deaths, and QALYs gained after the introduction of PSA screening. The researchers modeled various screening strategies, efficacies, and quality-of-life assumptions.
The investigators noted that per 1,000 men of all ages who were followed for their entire life span, they predicted that annual screening of men between the ages of 55 and 69 years would result in nine fewer deaths from prostate cancer (28% reduction), 14 fewer men receiving palliative (supportive but not curative) therapy (35% reduction), and a total of 73 life-years gained (average: 8.4 years per prostate-cancer death avoided). The number of QALYs that were gained was 56 (range: −21 to 97), which marked a reduction of 23% from unadjusted life-years gained. They found that to prevent one prostate-cancer death, 98 men would need to be screened and five cancers would need to be detected. Screening of all men between the ages of 55 and 74 would result in more life-years gained (82) but the same number of QALYs (56).
The researchers concluded that the benefit of PSA screening was diminished by loss of QALYs due to post-diagnosis long-term effects. Longer follow-up data from both the ERSPC and quality-of-life analyses are essential before universal recommendations regarding screening can be made.
Take home message:
This study used a new method: quality-adjusted life-years (QALYs) to quantify the harms and benefits of screening. They concluded that additional long-term follow-up was needed before PSA testing recommendations can be finalized. The harm from the test is a result of overtreatment with biopsies or surgery. The best course of action would be to have a PSA test. If it is abnormal and an invasive procedure is recommended, it would be prudent to obtain a second opinion. It is important to ascertain not only the urologic surgeon’s skill but also his “surgical aggressiveness.” During my years in private practice, I encountered some surgeons in a variety of specialties who were “surgically aggressive.”
Reference: The New England Journal of Medicine
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