Summary of New Proton-Therapy Studies Presented at November ASTRO Meeting

(December 2009)

While new proton-therapy studies and reports were being presented at the November, 2009 meeting of the American Society for Radiation Oncology (ASTRO), the American Cancer Society was reporting almost 1.5 million new cases are expected to be diagnosed in the U.S. this year, and over half a million Americans are expected to die of cancer. At the  51st Annual ASTRO Meeting, the good news reported is a growing number of treatments are available to combat the disease, including proton beam therapy for delivering precise radiation treatment with minimal to no side effects.

For example, Dr. Carl J. Rossi of Loma Linda University Medical Center, reported on LLUMC’s latest study: “There is a lot of interest in proton therapy for prostate cancer. This first-of-its-kind study provides evidence of the benefits of proton beam therapy. It is safe, effective, and has minimal side effects. This study proves the importance of giving high radiation doses to prostate cancer patients with low-and intermediate-risk disease because it demonstrates that even these favorable patients still benefit from the extra high-dose treatment.”  A boost of the highly targeted form of radiation therapy may prevent prostate cancer from coming back, Rossi’s study of some 400 men suggests. “The beauty of the treatment,” Rossi says, “is that it spares normal, healthy tissue from radiation. We have exquisite control over where the radiation goes into the body. And because we can target the radiation right to the tumor site, we can use much higher doses of radiation than we can with conventional radiation.”

Dr. Rossi explained that the patients treated with extra proton therapy were almost 50% less likely to need adjuvant hormone therapy at a later date, thus avoiding side effects that can affect a patient’s quality of life.

A second positive study reported at ASTRO, and the first of its kind issued by the University of Florida Proton Therapy Institute, some three years after its opening, showed that few prostate cancer patients had severe side effects within one year of treatment. Of 212 men studied, there were only two instances in which side effects required some type of additional treatment, and some men needed certain medicines. The results are all the more impressive because the study involved higher doses of radiation than have been used in similar research, noted
Dr. Nancy Mendenhall, medical director. “This is our very first report,” Dr. Mendenhall said, noting that most clinical trials take years to yield results.

She pointed out the results are only preliminary and her researchers will continue to follow this group for years to come. A Ft. Myers health-care consultant, Walt Justice, is a believer. He had early-stage, but aggressive prostate cancer. He said: “In the worse case scenario, if it didn’t work, I could go back (to other options he considered).” He found he didn’t need to go anywhere else. His cancer went away and stayed away, with no side effects. “I was convinced this was the right place to be, and I’m convinced I was in the right place today.”

“The Holy Grail of radiation oncology is to deliver more radiation to the target and spare healthy tissues and organs, “ added Dr. Farzan Siddiqui, a radiation oncologist at Henry Ford Hospital in Detroit, at the ASTRO meeting.

Dr. Andrew Lee, Associate Professor of Radiation Oncology and Director of the Proton Center at M.D. Anderson Cancer Center gave this perspective:  

This study (the Rossi report) provides an update of one of a few mature randomized dos-escalation trials in the U.S. The durable PSA control rates for the higher dose escalation provides further validation for the use of higher radiation doses in the absence of hormone therapy. The similar side effect profile between the low-and high-dose arms suggests that the use of more conformal techniques (i.e. proton therapy) is able to allow safe escalation of radiation dose. This was not the case when X-ray therapy was used in a prior randomized trial from M.D. Anderson.

This study provides further support that proton therapy is an effective treatment in prostate cancer and demonstrates one of the best PSA control rates from any mature perspective study using external beam radiotherapy. Few centers have proton therapy, but it does provide a rationale for dose-escalation radiation therapy in patients with prostate cancer, including those considered at low risk for subsequent failure, What is not known, is whether the use of short-course hormone therapy with intermediate doses of radiation may achieve similar results.

Dose –escalation radiation therapy should be considered in patients with localized prostate cancer. Proton therapy is an effective and safe way to achieve higher radiation doses for prostate cancer.



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