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Extended study follow-up confirms low value of annual PSA screenings
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Men who receive annual screenings for prostate cancer have no better mortality rates than those tested less frequently, according to a randomized follow-up study published in Cancer.
“Extended follow-up of the Prostate, Lung, Colorectal, and Ovarian Cancer (PLCO) Screening Trial (up to 19 years) continues to show no prostate cancer mortality benefit of screening with PSA and digital rectal examination for the intervention arm versus the control arm,” Paul F. Pinsky, PhD, chief of the early detection research branch at NCI, and colleagues wrote. “Because of the high rate of control-arm PSA testing, this finding can be viewed as showing no benefit of organized screening versus opportunistic screening with PSA.”
Behind lung cancer, prostate cancer is the second leading cause of cancer death among men in the United States. Although PSA screening has been ongoing for more than 25 years, two large-scale randomized trials showed conflicting results on the benefits of annual screenings.
A 13-year-follow-up by the European Randomized Study of Screening for Prostate Cancer (ERSPC) showed that men who had annual screenings had an RR for prostate cancer mortality of 0.79. In contrast, a 13-year follow-up of the PLCO trial showed the intervention arm to have an RR of 1.09, leading the U.S. Preventive Services Task Force to recommend against annual screening in 2012.
In their study, Pinsky and colleagues updated the mortality rates of the PLCO trial with follow-up extended to up to 19 years from randomization.
“In addition to providing a more stable estimate of the RR based on more prostate cancer deaths, this updated analysis also allows an examination of the longer-term effects of prostate cancer screening,” Pinsky and colleagues wrote. “This is especially relevant because of the natural history of the disease.”
Researchers of the PLCO trial randomly assigned men into an intervention arm (n = 38,340; 86% white) or control arm (n = 38,343; 84% white) from 1993 to 2001. The intervention arm received annual PSA screenings for 6 years and digital rectal examinations for 4 years. The control arm received usual care, which sometimes included opportunistic screening.
The median follow-up was 14.8 years in the intervention arm and 14.7 years in the control arm, with a maximum follow-up of 19.1 months in each group.
There were 255 deaths of prostate cancer in the intervention arm (2.8%) and 244 deaths of prostate cancer in the control arm (2.6%), equating to an RR of 1.04 (95% CI, 0.87-1.24). The RR for all-cause mortality was 0.97 (95% CI, 0.95-1).
The most prevalent cause of death in both arms was another cancer (excluding lung and colorectal cancer) — which occurred in 21% (n = 1,933) of the intervention arm and 20.1% (n = 1,882) of the control arm — followed by ischemic heart disease (18.4% vs. 17.6%) and other circulatory disease (14.3% vs. 14.6%).
It was estimated that 99% of the men in the intervention arm received PSA testing during the trial — of whom 84% reported annual screening — compared with 86% in the control arm, 46% of whom underwent annual screening.
“With a median follow-up of almost 15 years, the majority of deaths from prostate cancer (approximately 60% in each arm) still occurred in cases diagnosed during the screening phase of the trial (first 6 years),” Pinsky and colleagues wrote. “This indicated the need for long-term follow-ups perhaps even longer than 15 years, to fully capture the potential mortality effects of PSA screening.”
Data from the ERSPC trial — which had less screening in the control arm — showed PSA screening has led to a 44% reduction in prostate cancer mortality in Sweden, a 20% reduction in the Netherlands, and a 15% reduction in Finland, Roman Gulati, MS, of the division of public health sciences at Fred Hutchinson Cancer Research Center, and Peter C. Albertsen, MD, MS, professor of surgery and program director at UConn Health, wrote in an accompanying editorial.
Considering the high rates of screening in both arms of the PLCO trial, researchers should consider whether they are better ways to screen, Gulati and Albertsen wrote.
“Even if we confirm that one approach to PSA testing can lower prostate cancer mortality, an equally important question is whether we have identified a sufficiently effective approach,” they wrote. “Furthermore, any benefit must be weighed against the known harms of screening, including the risks of unnecessary diagnosis and treatment of indolent disease, and possible tradeoffs set in the context of competing demands for scarce health care resources.
“… It is important to recognize that better ways of screening are intimately linked to the ways in which the initial treatment and follow-up care are provide,” they added. “For example, aggressive screening detects many slow-growing cancers that do not require treatment.”
Recently results from the Prostate Testing for Cancer and Treatment (PROTECT) study also showed low prostate cancer mortality rates among men with screen-detected localized disease randomly assigned to definitive treatment or active monitoring after 10 years of follow-up, Gulati and Albertsen wrote.
“However, the risk of metastasis was higher for men randomized to active monitoring, underscoring the need for caution with this approach,” they added. “Longer follow-up is needed, but this trial shows that the evaluation of screening outcomes cannot be separated from associated treatment decisions.”– by Chuck Gormley
Disclosure: Researchers report no relevant financial disclosures.
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