So we’ve spent a little time
giving some focused attention
on screening for breast cancer and
screening for colorectal cancer,
and now I’m going to cover screening for
some other important forms of cancer,
and just a hint, it’s prostate and lung.
All right, let’s get going.
Start with a case.
You have a 51-year-old asymptomatic man,
no family history of prostate cancer.
He wants to know if he should be
screened for prostate cancer.
What can you tell him regarding prostate
cancer screening recommendations
from the US Preventive
Services Task Force?
A. He should be screened with
a digital rectal examination
plus a prostate-specific
or B. He should be
screened with a PSA only,
C. He should not be screened
for prostate cancer,
or D. There is insufficient
evidence to recommend
for or against prostate
The answer is C.
He should not be screened
for prostate cancer.
It’s easier to think about D because
the Preventive Services
Task Force is ambivalent
because of a lack of evidence about
a lot of different conditions,
but they recommended against
screening for prostate cancer
due to a lack of certain benefit
and some risk of harms.
So let’s look at the
epidemiology of prostate cancer.
In terms of how common
prostate cancer is,
it certainly seems to meet the criteria
for screening from that perspective.
The lifetime prevalence is nearly 17%,
60% of those tumors are
diagnosed above age 65 years,
and as you get older, 70%
of prostate cancer deaths
are found among men who
are 70 years old or more.
However, that has to be counterbalanced
by the overall risk of mortality.
Prostate cancer is associated with
only 3% of all deaths among US men.
So despite those statistics
of how common it is
and how it tends to produce death
among older men in particular,
it’s a fairly low impact
on overall male mortality.
And in fact, only about
half of prostate cancers
during a man’s lifetime.
The others never become symptomatic,
and therefore, really don’t
cause any kind of problems,
and that’s the tricky part
with prostate cancer.
Common and can be aggressive,
yet also can be frequently indolent
and, therefore, never really affect
a man who’s already 84 years old
who develops it for example.
So one thing I’ll advocate is is that the
digital rectal examination really adds nothing,
and they’ve done some research on this,
adds nothing to PSA testing alone.
Patients hate it, and rarely it’s been
associated with cases of moderate bleeding
or even infection and
sometimes severe infection
that’s related to paraspinal abscess.
And so therefore, there are
some risks with just doing the
digital rectal examination besides
just embarrassment alone,
and in general, my rule is I
don’t see much of an indication
for doing the digital rectal examination
at all among asymptomatic patients.
Very different if you’re having a
lower urinary tract symptoms or
rectal bright red blood, then, sure,
but that’s a symptomatic patient.
Asymptomatic patients for screening
purposes, I don’t do a DRE.
So what we do employ is
generally a PSA testing.
And the most effective
threshold for saying
what’s normal versus
abnormal is controversial.
The most common threshold
is 4 mcg per liter.
Above 4 mcg per liter is considered
suspicious or a positive test.
But that threshold is associated
with a very high false-positive rate
and it has a not insignificant
You really want to see a very low, low
false-negative rate with a screening test.
Now, what do we do when we
get a positive PSA test?
We refer to urology and they’re probably
going to get transrectal ultrasound
with biopsy assuming that this is
asymptomatic average-risk patient.
So just understand that the PSA is
associated with a higher rate of detection
for prostate cancer once
they do that testing,
the relative finding of cancer is
63% higher versus no screening.
But up to a third of
men experience some
substantial side effects
after a prostate biopsy.
So that prostate biopsy test is
expensive, it’s uncomfortable,
and is associated with bleeding and
some other substantial side effects,
which shouldn’t affect
people in the long run,
but it can certainly be uncomfortable
around the time of the procedure.
So there are two major
randomized trials of
prostate cancer screening
that are worth knowing.
One is the Prostate, Lung, Colorectal, and
Ovarian Screening Trial,
or PLCO Trial, that was
done in the United States,
enrolled 77,000 men between
55 and 74 years of age.
They found no difference in a
screening group based on PSA
versus a control group with no screening
in terms of prostate cancer mortality.
Even though in the screening
group, as predicted,
they found more
prostate cancer itself.
Limitation on this trial,
the major limitation,
is that there was
over half of the group that was
not supposed to get a PSA testing
as part of the trial got PSA testing
in their clinical practice.
And so, it was a negative trial that
made PSA testing look ineffective,
but they did have this significant
limitation attached to it.
The European Randomized Study of Screening
for Prostate Cancer was even larger,
160,000 men aged between
55 and 69 years of age.
They did find a statistically
of prostate cancer
mortality with screening,
and this is important because it’s the
only major prospective trial to do so.
Yet the efficacy was only 1.28 reduced
deaths per 1,000 men enrolled.
So the number needed to screen
in this case was really high,
781 men needed to be screened to
prevent one prostate cancer death.
And in fact, they also
calculated that 27 cancers
would have to be treated to prevent
that one additional death as well.
So that’s a lot of time, a lot of money,
a lot of morbidity and side effects
when we think about cancer treatment in
order to prevent that one cancer death.
So while there was a statistical
significance in this trial,
you know, how it plays out in
terms of clinical significance
and how it should play
in the recommendations,
that’s a pretty
And yet we know that 90% of
men with prostate cancer
decide to undergo
And that therapy is highly effective
for treating prostate cancer,
but do recall, radical prostatectomy, which
is one of the more popular choices still
associated with rates of urinary
incontinence of about 20%
and erectile dysfunction
in up to half,
and those are significant
impacts on quality of life.
Urinary incontinence really
changes people and their habits.
I mean think about like going to movies,
long car trips, everything becomes a risk,
and therefore, patients can be
really debilitated and depressed,
who have urinary incontinence.
So there are some less
invasive treatments as well.
What about external beam radiation
therapy or implanted brachytherapy?
Those are also effective, can be
similarly effective and less invasive,
but still some risks for chronic
loose stools, for urethra stricture,
still significant rates
of erectile dysfunction.
So let’s look at recommendations.
The Preventive Services Task Force
says that harms outweigh benefits
and they recommend against.
The American Cancer Society, which is
generally pro, pro cancer screening
advocates shared decision-making
for people at age 50
and for African-Americans
beginning at age 45.
The American College of Physicians
is a little bit discouraging,
but recommends some form of
shared decision-making as well.
And the time to do shared decision-making
is before you order the PSA, by the way,
because after you order the
PSA and it comes back at 6,
now you’re kind of obligated to recommend
that the patient go see a urologist
and get further testing
for prostate cancer.
So it’s really a decision best
made before they go to the lab.
American Urological Association recommends
just shared decision-making
between 55 and 69 years of age,
and the American Academy
of Family Physicians
recommends against routine
prostate cancer screening.
And again, this is for
average-risk men, not men,
say, with a family history
of prostate cancer.