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 can't 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".|
During surgery 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. (It's also one of the reasons he produced the DVD of his surgery, so he could teach other surgeons how to do this -read story)