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Understanding Surgical Margins after Radical Prostatectomy

Understanding Surgical Margins after Radical Prostatectomy

Updated: 12/21/2015

In an ideal world, after radical prostatectomy, your pathologist would send a triumphant report to your surgeon declaring you cancer-free. For some patients, however, the pathologist's report is more ambiguous. It may describe your margins, which are the edges of your removed tumor, as positive because they show some cancer cells. Or your margins may be close, meaning that your cancer is just a hair's breadth away from the edge of the specimen.

Good News about Close Margins

According to Jonathan I. Epstein, M.D., a pathologist at Johns Hopkins Medicine, close margins are almost always negative. Dr. Epstein completed a study of patients whose tumors were particularly close (less than two-tenths of a millimeter) from the surgical margin. Even though there wasn't a comfortable cushion of tissue between the tumor and the edge of the prostate, those patients did just as well as patients with more separation between the tumor and the margin.

Causes of Positive Margins

Even if your surgical margins are positive, this does not necessarily mean that some cancer cells were left behind. The following reasons explain how you can be considered cured but still have positive margins:

  1. When the surgeon cuts across the last few tumor cells, what appears to be remaining cancer is actually a cross-section of the perimeter of the tumor. Even though it looks like it's a positive margin, there's really nothing left in the patient. The act of surgery itself finishes the job, killing any remaining cells. Since no cut or injury to tissue happens in a vacuum, the area around the cut is affected too. (When the surgeon cuts across tissue, the blood supply is cut off and that can kill off the last few tumor cells that may have been left behind.)
  2. In many cases, a positive margin turns out to be an artificial one. During the surgical removal of the prostate gland, the surgeon, nurse and pathologist have to handle the delicate tissue. Because there's so little tissue next to the prostate (about two-tenths of a millimeter), that tissue can get disrupted very easily and make it appear that the tumor is at the margin. However, there may be some additional tissue that just got disrupted during the handling of the specimen. In other words, a few good buffer cells got rubbed off.
  3. The sticky cell phenomenon may also cause positive margins. When cancer reaches beyond the prostate to invade nearby tissue, it produces a dense scar tissue that acts like super glue. As the surgeon removes the prostate, this thick scar tissue sticks to the surrounding cancer cells, picking them up like a lint brush. In some cases, although the pathologist may see cancer cells at the margin, and declare positive surgical margins, there are no cancer cells left inside the patient. The sticky scar tissue took them all away.

Dr. Epstein studied several instances of positive margins. First, he removed the prostate and examined it closely. If he suspected that some cancer cells were present, he went back and cut out more of the surrounding tissue. From a pathology standpoint, he had two separate specimens. One was the prostate, and one was the extra tissue. The extra tissue was the neurovascular bundle that he initially planned to leave behind in the patient, but decided to remove. Even when there appeared to be a positive surgical margin at the edge of the prostate, in 40 percent of these patients, there turned out to be no cancer cells left behind in the adjacent tissue.

So if you find out you have a positive or close margin following surgery, don’t panic. It doesn't necessarily mean that you need some other form of therapy.

What if cancer cells are left behind?

But what if a positive margin truly means that there's still cancer in the area? You may still be cured with radiation to the prostate bed, the area where the prostate used to be. But there are other factors to consider.


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