The downside to
prostate cancer screening is that, for some men, it's too good:
It finds cancer that probably doesn't need to be found. "There is
a tradeoff," says H. Ballentine Carter, M.D., professor of urology
and oncology. "Some men are diagnosed and treated unnecessarily."
In these men, prostate cancer is very slow-growing. It never spreads
beyond the prostate, and never becomes aggressive.
About half of men today are diagnosed
with this "low-risk" prostate cancer — cancer that is too small
to be felt during a rectal exam, with a Gleason score of 6 or lower,
in men with a PSA below 10 nanograms per milliliter. "This is going
to be an increasing issue as our population ages, and as more men
undergo regular screening for prostate cancer," Carter says.
This is not watchful waiting, it’s
proactive monitoring. And so far, it
does not appear that the window
of curability is being lost.
Some of these men, Carter believes,
may be ideal candidates for something new. "Starting with the assumption
that men with low-risk prostate cancer can almost always be cured
with surgery, and that for younger men, surgery is ideal, there
is a subset of older men for whom expectant management with curative
intent may be an ideal option, because of the low risk of disease
progression." This is not watchful waiting; it's proactive monitoring.
Carter, who is leading the research
in this new area, started a program at Hopkins in 1995 designed
to identify men with low-risk prostate cancer, follow them closely,
and intervene with curative intent (surgery or radiation) only if
the disease progresses. Over the last decade, about 400 men, with
an average age of 67, have entered this program. First, these men
undergo at least a 12-core biopsy, to make sure their disease has
not been underestimated. Then, they are followed closely, with a
PSA and rectal examination every six months, and a yearly biopsy.
Progression is defined by what the pathologist sees in the biopsy
— cancer present in more than two cores, or in more than half of
any one core; or a Gleason score of 7 or greater — or an unusual
increase in PSA that prompts another biopsy.
"The trigger for intervention in
these men is biopsy evidence that there is more disease, or higher-grade
disease," Carter says.But what about the critical "window of curability?"
Could men miss their chance of being cured, even with this close
monitoring? Carter and colleagues recently addressed this question
in a study, published in the Journal of the National Cancer Institute.
"We compared the surgical outcomes of 38 men who entered the surveillance
program and subsequently underwent surgery — on average, two to
three years later — with 150 similar men who qualified for the program
but chose to undergo surgery immediately after their diagnosis."
The scientists found that an equal number of men in both groups
turned out to have curable disease.
Carter stresses that this approach
is still investigational. However, so far — using this careful plan
for enrolling patients and following them — it does not appear that
the window of curability is being lost.