Nerve-Sparing and Positive Surgical Margins
What happens to the nerves responsible for
erection if cancer has escaped the prostate?
Can they still be preserved? Sometimes,
cancer ventures only slightly beyond the
prostate -a distance significant enough for
the surgical margins, the edges of the
removed tissue, to be considered positive,
but really just a matter of a couple of millimeters.
If this happens near the neurovascular
bundle, one of two tiny packages of
blood vessels and nerves adjacent to the
prostate that are responsible for erection, is
that bundle automatically doomed?
Not necessarily, says Patrick C. Walsh,
M.D. "When cancer spreads microscopically
outside the prostate, the tumor rarely
extends more than one or two millimeters
into the adjacent soft tissue. This is because
cancer cells seem to need the environment of
the prostate." Walsh uses the example of
seeds and soil: "The soil is the tissue of the
prostate, and the seeds are the prostate cancer
cells. If they spread without the proper
soil, they canít survive."
Prostate cancer cells can eventually learn
to make a habitable environment outside the
prostate, but this process is complicated and
can take years, he adds. (A lot has to do with
the Hedgehog pathway- read story)
In a recent study, urology resident David
Hernandez, M.D., along with pathologist
Jonathan Epstein and Walsh, reviewed 100 men who had evidence of extension of
cancer outside the prostate, in the area of
the neurovascular bundle.
"It takes a great deal of experience,
and also tactile sensation, in
determining exactly when and
where it is possible to preserve the
neurovascular bundle, and where
it is necessary to remove it".
Walsh, who has long respected the use of
tactile sensation -what he can feel of the
prostate and surrounding tissue - during the
operation, determined that it was safe to
preserve the nerve bundle in 84 of the men.
He excised the bundle and surrounding tissue
in the remaining 16 men.
Later, when Epstein examined the removed
surgical specimens, he found that the frequency
of positive margins was only 5.8 percent -
six men. This low rate of positive surgical
margins is essentially the same as Walsh
achieves in all of his patients. It is also identical
to the number of positive surgical margins
reported by another urologist - except
that urologist widely excises the neurovascular
bundle in 65 percent of his patients.
Of the 100 men in this study, 86 percent
of the men were potent 18 months or more
after surgery. Walsh believes the key to success
here is the ability to feel the prostate
and surrounding territory during surgery -
and the expertise to interpret those findings.
"It takes a great deal of experience, and also
tactile sensation, in determining exactly
when and where it is possible to preserve the
neurovascular bundle,and where it is necessary
to remove it," he says. This is why he
believes that the open radical prostatectomy
remains the "gold standard" for treatment.
(Itís also one of the reasons he produced the
DVD of his surgery, so he could teach other
surgeons how to do this - read story)