The co-authors of Invasion of the Prostate Snatchers, blog alternate posts weekly. We invite you to post your comments.

Tuesday, November 10, 2015

Photons or Protons? You Choose


Following in the footsteps of robotic surgeons, prostate cancer continues to go high-tech. Radiation, for instance, is no longer just radiation. There are now numerous different ways to deliver it. But the two methods I want to write about here are Intensity Modulated Radiation Therapy (IMRT), and Proton Beam Therapy (PBT).

The predominant method in the U.S. for the past decade is IMRT, a complex procedure that precisely targets the prostate gland with multiple beams of high energy light (photons) at different angles and intensities while significantly lowering the risk of damage to the surrounding tissues and organs.  This greater accuracy in targeting also allows the therapist to maximize the radiation dose to the tumor.  IMRT has at least as effective a cure rate as surgery, and without the risks and side effects of a major surgical procedure.

Having said that, I have recently been checking out Proton Beam Therapy, a form of radiation that targets the tumor with charged particles called protons. Several decades ago, Loma Linda University in California was the first to begin administering PBT. At that time, I had a friend who, at 55, developed prostate cancer and was one of the first patients at Loma Linda when proton therapy was at a very early stage.  Bill has been free of cancer for over twenty years, and only recently had a rise in PSA and is discussing further treatment.

Since then, thanks in part to marketing hype, PBT is becoming increasingly popular.  Now, M.D. Anderson, Harvard, and the University of Florida in Jacksonville, are among the major medical centers that have made PBT available. And The Mayo Clinic is building two proton therapy centers (one in Rochester, one in Arizona) at a cost of $380 million. Naturally PBT costs considerably more than IMRT.

When weighing treatment options, patients generally consider two main factors: potential side-effects, and successful outcome. So how do these two therapies measure up? Well, there is considerable controversy in the urologic community. The good news is both therapies have a high cure rate. Studies that have tried to compare IMRT with Proton therapy indicate that the outcomes are quite similar and that the side effects are comparable.  No large randomized trials have been published that directly compare patient outcomes with the different techniques.  So in the end, a treatment decision usually depends on such variables as patient preference and doctor preference.

It is reasonable, therefore, to keep in mind that any medical center that has invested an astronomical amount of money on equipment will end up wanting to use it.

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