Screening linked to approximately 32% decrease in prostate cancer deaths
“Men trying to follow the advice on whether they should get screened for prostate cancer have long been confused, since guidelines and recommendations keep changing. Now, in the latest analysis of data published in the Annals of Internal Medicine, researchers conclude that testing does help save lives from the disease and is linked to as much as a 32% decrease in prostate cancer deaths, compared to men who aren’t screened.” according to TIME Health’s Alice Parks in “Getting Tested for Prostate Cancer May Be Worth It After All”.
New research led by Ruth Etzioni, PhD, of the Fred Hutchinson Cancer Research Center, Seattle, Washington, re-analyzed two major prostate cancer studies that had conflicting results. Parks, contrasting the original findings, “The U.S. study, the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO), did not find any difference in deaths from prostate cancer among men 55 to 74 years who were screened with PSA and men who were not screened. The European Randomized Study of Screening for Prostate Cancer (ERSPC) which included men 55 to 69 years, however, found that PSA screening led to a 21% lower risk of dying from prostate cancer during the study follow-up compared to men who didn’t get screened.”
Upon re-analysis, both major studies showed reduction in death among screened men
“The new analysis concludes that both studies do, in fact, show a reduction in the risk for death from prostate cancer among men who were screened. The new analysis of data used a mathematical model to account for differences in the two studies. Adjusting for implementation compliance and practice settings, it found that both the ERSPC and PLCO provide compatible evidence that screening reduces prostate cancer mortality,” according to Roxanne Nelson for Medscape.
Adjustments allowed comparing ‘apples to oranges’
One adjustment accounts for the European practice of recommending prostate biopsies for men with lower prostate specific antigen (PSA) scores than common for U.S. patients. This could have lead to earlier prostate cancer diagnosis and treatment for ERSPC trial subjects compared to U.S. patients.
Re-analysis also corrected for the fact that in the U.S. study (PLCO), some men in the ‘non screened’ group actually had PSA screening at some point and may have received treatment before the study.
“The new analysis showed a 25% to 31% lower risk in the ERSPC and a 27% to 32% lower risk in the PLCO for dying from prostate cancer among men who were screened compared to men who were not screened,” writes Nelson.
“Nail in the coffin to the argument that screening does not prevent prostate cancer mortality” — Dr. Jonathan Shoag
Jonathan E. Shoag, MD, New York-Presbyterian Hospital, New York City had himself re-analyzed only the U.S. PLCO trial last year. “Up until recently, there was the widespread belief in the medical community that PSA screening did not save lives.” Shoag commented on the latest re-analysis of both studies, emphasizing its importance, “as it shows that when accounting for control-group contamination and other study differences, both trials actually show a comparable mortality benefit to screening. This should serve as the nail in the coffin to the argument that screening does not prevent prostate cancer mortality.”
Will re-analysis shift US Task Force prostate cancer screening recommendations?
“This is a big turnabout. The PLCO was originally reported as not showing any effect on prostate cancer mortality, a finding that was a big factor on the US Preventative Services Task Force’s (USPSTF’s) decision to recommend against routine PSA screening in 2012,” says Roxanne Nelson.
Historical significance of the PSA blood test for prostate cancer screening
Giving the historical importance of the new study, Parks explains, “For decades since the 1980s, doctors have recommended that men start to get an annual blood test that can detect possible signs of growing tumors: one for the prostate specific antigen (PSA). But PSA testing has always been tricky, since prostate cancers (unlike breast cancer tumors) tend to grow more slowly—so slowly, in fact, that most men are more likely to die of something else other than prostate cancer. That made treating prostate cancer detected by the blood test less black and white. It also led many men to get biopsies—a relatively safe procedure, but one that still carries potential complications like infections—and even treatment with surgery, radiation or other therapies to remove the tumors, despite the fact that they were slow-growing.
In the U.S., that led to a surge in what some doctors view as unnecessary medical treatments that put men at risk without providing them much benefit. (For most men, prostate cancer isn’t fatal.) So in 2012, the U.S. Preventive Services Task Force (USPSTF) issued a draft recommendation that most men ages 55 to 69—except for those who have a family history of the disease or are at high risk of developing the cancer—should not get PSA testing at all.”
Conflicting results affected screening recommendations
The 2012 USPSTF recommendations were largely centered on the two original studies—the U.S. PLCO and the European ERSPC—which showed seemingly conflicting results. “Given the uncertainty, and the risks of treating cancers that weren’t aggressive, the USPSTF decided there wasn’t convincing enough evidence to recommend PSA screening.”
But, in April 2017, based on early evidence that less screening was resulting in more cases of advanced prostate cancer, the Task Force modified its recommendation against general PSA testing. They currently suggest men age 55 to 69 resume individual discussions of screening related to their risk of prostate cancer with their doctors. “The current study will likely play a role in any revised guidelines on prostate cancer screening,” states Nelson.
Screening recommendations of Prostate Cancer Foundation of Chicago
Prostate Cancer Foundation of Chicago commends the efforts of author Alex Tsodikov and colleagues to extend the utility of the two major original studies through re-analysis. Both PLCO and ERSPC are important randomized controlled trials, which top the hierarchy of clinical study designs.
Prostate Cancer Foundation of Chicago (PCFC) also applauds USPSTF’s decision to modify their 2012 recommendations, now calling for patient-physician discussions on whether and when to screen. PCFC supports screening starting at age 50, even if just to establish a baseline PSA score. Annual screening is recommended earlier — at age 40 — for African Americans and men with a family history of prostate cancer. Screening and discussion is especially important since prostate cancer can be considered as a spectrum disease, with varied manifestations and a wide range of aggressiveness, according to Brian J. Moran, M.D., PCFC Medical Advisor and Chicago Prostate Cancer Center (CPCC) Medical Director.
About Prostate Cancer Foundation of Chicago
PCFC shares prostate cancer treatment advancements, working hand-in-hand with CPCC to measure patient outcomes for research studies. Click Prostate Cancer Foundation of Chicago for ways to stay informed about prostate cancer and screening recommendations, through Informational Support Groups, current clinical research and recent publications.