Almost Half of Deaths from Prostate Cancer Can Be
Predicted by PSA Before Men Reach Age 50
Earlier 2010 study in BMJ showed PSA level at age 60
is strongly predictive of the risk of death from prostate cancer by age
"As it turns out, the best way to
determine risk is a single PSA before the age of 50."
April 17, 2013 - Prostate specific antigen (PSA)
screening is widely used for the early detection of prostate cancer, but
remains highly controversial, as it became widespread long before
evidence to prove its value. There is now evidence that PSA screening
can reduce prostate cancer mortality in men who would not otherwise be
screened. However, this can come at considerable harm.
But, focusing prostate cancer testing on men at
highest risk of developing the disease is likely to improve the ratio
between benefits and the harms of screening, suggests a paper published
yesterday on bmj.com.
As there is little evidence to support many aspects
of screening guidelines, researchers from Sweden and the USA carried out
a case-control study taking data from the Malmo Preventative Project (MPP)
cohort, in an attempt to develop an evidence-based scheme for prostate
A previous study from the MPP, published in the BMJ
in 2010, demonstrated that PSA level at age 60 is strongly predictive of
the risk of death from prostate cancer by age 85.
The Malmo cohort included 21,277 men aged 27 to 52
who participated in the MPP between 1974 and 1984. All these men gave a
blood sample. A smaller group of these men were then invited to provide
a second blood sample about six years later: 4922 (72%) of those
The researchers focused their studies on men close
to age 40, mid-to-late forties (45-49) and early-to-mid fifties (51-55).
Within 25 to 30 years, 44% of deaths from prostate
cancer occurred in those with the top 10% of PSA levels at age 45-49, a
PSA of about 1.5 ng/mL or more. The risk of prostate cancer death was
more than 10 times greater in this group compared to men with the lowest
25% of PSA levels.
The researchers questioned whether PSA screening
should start at age 40, mid-to-late 40s or early 50s: they found that
even for men with PSA in the top level at age 40, the risk of metastatic
prostate cancer was very low at 0.6%, after 15 years of follow-up. The
researchers say that due to this, it would be difficult to justify
initiating PSA testing at age 40 for men with no other significant risk
Risk much higher to top level PSA at age 45-49,
higher again at 51-55
In contrast, the risk of developing metastatic
prostate cancer within 15 years is close to three-fold higher for men in
the top level PSA at age 45-49 (1.7%) and close to ten-fold higher at
age 51-55 (5.2%). This suggests that initiating PSA screening after age
50 would leave a significant proportion of men at elevated risk of later
being diagnosed with an incurable cancer.
The researchers also looked at screening intervals:
results showed that the absolute risk of metastatic cancer remains very
low within 15 years follow-up for men with PSA in the lowest levels and
as such, a screening interval less than five years for these men is
The researchers conclude that PSA levels are
informative of the current risk of cancer as well as being “predictive
of the future risk of prostate cancer” and any cancer-specific death.
They say that screening programs can be designed so as to “reduce the
risk of over-diagnosis while still enabling early cancer detection for
men at highest risk of death from prostate cancer”. As it turns out, the
best way to determine risk is a single PSA before the age of 50.
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