screening catch cancers early and thus decrease mortality from
these diseases? To answer this question, ten academic medical centers in
the United States screened 76,685 men and 78,216 women for prostate,
lung, colorectal and ovarian cancers.
Starting in 1993 and ending in 2001, the fifteen-year follow-up results focusing on prostate
cancer were published this month in the journal Cancer
show little difference in mortality between men screened annually and
the control group, some of whom chose to be screened occasionally.
‘Yearly prostate cancer screening does not appear to decrease mortality from this disease. The findings suggest that screening only those with higher risk, at the right schedule, could save lives.’
According to researchers, the results don't necessarily negate the value
of prostate cancer screening, but imply that within the data of this
massive trial are clues that inform personalized decisions for subsets
of this prostate cancer population.
"What we can see from these results is that most men diagnosed with
prostate cancer will not die from their disease. In 15 years, people on
the study died from lots of other things. However, we can also see that
now we need to focus on discovering the men that will," says E. David
Crawford, investigator at the University of Colorado Cancer Center
and study co-author.
Specifically, in the intervention arm that received annual prostate
cancer screening, 255 men have died of prostate cancer since the start
of the trial. In all, 244 men in the control arm, who did not receive
annual screening (but may have received self-directed intermittent
screening), died of prostate cancer. By comparison, 1,933 and 1,882 men
in the experimental and control arms, respectively, died of other
cancers. Slightly more in each group died of heart-related conditions.
According to Crawford, these data imply that some men need not be screened for prostate cancer.
"For example, we have since shown that men with PSA lower than one
have only about a 0.5% chance of being diagnosed with prostate
cancer within 10 years," Crawford says. Administering a PSA test first
and then not screening men with PSA less than one would save billions of
dollars in healthcare costs every year.
However, in addition to discovering no decreased mortality with
yearly prostate cancer screening compared with intermittent screening,
Crawford suggests that these results could be used to discover men who
do, in fact, benefit from careful monitoring.
"I treated a guy who'd been diagnosed in his 40s," says Crawford.
"We did surgery, but then a year later he was diagnosed with melanoma.
It turned out that at the same time, his sister was diagnosed with
triple-negative breast cancer and died within the year. Being diagnosed
with prostate cancer in your 40s is a red flag that there might be a
germline mutation to blame, predisposing these men and maybe family
members who share the mutation to more, and more aggressive cancers. The
PLCO shows that most men don't benefit from screening, but if we could
have used the data to spot this guy, maybe we could have even tested his
sister as well."
And so the takeaway from this retrospective on a massive study, 15
years after the completion of data gathering, is that despite what many
have characterized as failure - after all, yearly screening did not
result in overall lives saved - is that inside this data (or in related,
follow-up studies) may still exist clues that could stratify prostate
Alongside the risks and costs of over-diagnosis and over-treatment
that come with screening the entire population of men for prostate
cancer still exists hope that screening only those with higher risk, at
the right schedule, could save lives.