POSTED: September 04, 2015

PCa & Irradiating Lymph Node

One of my patients asked the following question, which I answered in Prostate Forum Volume 14 Number 6.

Dear Dr. Myers:

I understand one of your standard protocols is to irradiate the lymph nodes if the cancer is found there by a PET scan or Feraheme MRI. This is in the context of a rising PSA after definitive treatment and hormone naive PC, with no other evident metastasis. Could you please explain how this might result in complete remission or even cure? Is it possible that the prostate cancer will only be in the lymph nodes and not in the blood stream as circulating tumors cells, only to take hold someplace else after the lymph nodes have been irradiated?
My answer: The answer to your question is that yes, for many men the cancer is very limited in its spread at this point. The result is that when these metastatic lesions are treated, the cancer goes into remission. My case is an illustration of this. In 1999, I had spread of the cancer to the lymph nodes in my pelvis. I also had prostate cancer cells in my blood and in the bone marrow at both sides of my pelvis. I had all detectable cancer radiated and had 18 months of hormonal therapy. It is now thirteen and a half years later and the cancer has never manifested itself in all these years.

My experience is not unique. Paul Lang and his colleagues at University of Washington showed that prostate cancer cells are found in the blood and bone marrow of men who are subsequently cured of prostate cancer by radical prostatectomy.
How does this happen? Most of the cancer cells found in the blood or bone marrow lack the capacity to grow. It turns out that the capacity to grow at a metastatic site is present only in a limited number of cancer cells. In general, prostate cancer cells making PSA are dead end cells with little or no capacity to grow. It turns out that the spread of prostate cancer is restricted by the limited capacity of this cancer to spread.

As a result, in men with PSA-only recurrent disease, the cancer appears to be limited to lymph nodes in the pelvis and lower abdomen. I would note the cancer spreads to these nodes via the lymphatic channels draining the prostate gland and not via the blood stream.

The odds of limited spread will diminish as the Gleason increases: limited spread will be the rule for Gleason 6, but uncommon for a Gleason 10

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