PSA Test for Prostate Cancer Doesn’t Save Lives: Study

FRIDAY, Jan. 6 (HealthDay News) — Annual screening for prostate
cancer doesn’t save lives, finds a new study that is unlikely to quell the
controversy surrounding routine prostate specific antigen (PSA)
screening.

“Organized prostate cancer screening when done in addition to whatever
background testing exists in the population does not result in any
apparent benefit, but does result in harm from false positives and
over-diagnosis,” said lead researcher Philip Prorok, from the Division of
Cancer Prevention at the U.S. National Cancer Institute.

“Men considering prostate cancer screening should be fully informed of
the implications of such testing before making a decision,” he added.

Experts have disagreed for some time on whether the blood test saves
lives or results in over-diagnosis and over-treatment. The new findings,
which extend prior results out to 13 years of follow-up, are published in
the Jan. 6 online edition of the Journal of the National Cancer
Institute
.

The study followed men enrolled in the Prostate, Lung, Colorectal and
Ovarian Cancer Screening (PLCO) Trial from 1993 to 2009, comparing results
for a group of men who had undergone screening with those for men who
hadn’t had testing. The men were 55 to 74 years old.

One group had PSA screening every year for six years and a digital
rectal examination every year for four years. The other men had regular
care, which in some cases included screening if requested by the patient
or doctor.

Compared to men getting usual care, the screened men had a 12 percent
relative increase in prostate cancer but a slightly lower rate of
high-grade cancer.

However, no difference in deaths was seen between the two groups.

This finding held true even after age, screening before the trial and
other medical conditions were taken into account, the researchers
said.

Prorok said that better treatment for prostate cancer may explain the
similar mortality results.

Among prostate cancer patients, death from other causes was somewhat
higher in the screened group (10.7 percent of 4,250 men with prostate
cancer) compared to the usual care group (9.9 percent of 3,815 men with
prostate cancer).

This indicates men who underwent PSA screening were over-diagnosed,
meaning the test picked up slow-growing tumors that probably weren’t
lethal, the researchers said.

“PSA testing and digital rectal examination screening as conducted in
this trial did not reduce prostate cancer mortality, but there was a
persistent excess of prostate cancer cases in the screened arm, suggesting
over-diagnosis of prostate cancer,” Prorok said.

Some prostate cancer experts disagree with the authors’
conclusions.

Dr. Anthony D’Amico, chief of radiation oncology at Brigham and Women’s
Hospital in Boston, said the results are invalid because the trial was
flawed.

According to D’Amico, 52 percent of those who received usual care had a
PSA screening. “That’s a serious issue which makes it very hard for the
study to show if any benefit exists for PSA screening,” he said.

Also, 15 percent of those who were supposed to get PSA screening never
did, D’Amico said. “So what you’ve got is a screening study in which 85
percent of the people got PSA screened on the screening arm and 52 percent
got screened on the control arm, which makes it impossible to ever measure
a difference,” he said.

Men should ignore this study, “because it has no relevance to PSA
screening,” D’Amico said.

D’Amico said he has more confidence in the results of a European study
published in 2009 in the New England Journal of Medicine, which
showed a 20 percent reduction in cancer mortality with PSA screening.

Men who can benefit most from screening are those at risk for prostate
cancer, particularly men who have a family history of prostate cancer,
African Americans and men over 60, D’Amico said.

Prorok acknowledged that the PLCO trial wasn’t perfect. “Nonetheless,
the contamination was not enough to eliminate the early diagnosis of
prostate cancers nor the persistent excess of cancers,” he said.

PLCO provides information about over-diagnosis, Prorok added. “Even if
the contamination did dilute a benefit compared to no screening, the
result of no mortality difference between the arms in PLCO could be
interpreted to suggest that more intensive screening is not beneficial but
does result in harm,” he said.

More information

For more information on prostate cancer, visit the
American Cancer Society
.

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