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Radiotherapy for Prostate Cancer has Evolved but Questions of Long-term Benefit of Newer Technologies Remain


(PHILADELPHIA)—In a review of the state of prostate cancer radiotherapy, researchers conclude that the menu of options available for men is expanding. However, given the lack of evidence proving the long-term benefit of some of the newer technologies, they say some of these treatments should not be used outside of clinical trials.

The report, in Volume 10, Issue 10 of the journal Nature Reviews Urology, was designed to give an overview of radiotherapy for prostate cancer to help physicians make informed personalized treatment decisions for patients. The study was conducted by researchers at Thomas Jefferson University's Kimmel Cancer Center.

But that won't be easy given lack of outcomes evidence for some of the treatments, and dearth of studies that compare one treatment with another, says the study's lead investigator, radiation oncologist Nicholas G. Zaorsky, MD.

In fact, in the study, the research team looked at almost 1,000 published studies, and narrowed their analysis down to 33 studies that they felt were rigorous and reported patient outcomes over an extended period of time after treatment.

"It is important to personalize therapy to individual patients so that they receive the best care. Patients who choose radiotherapy should be provided with all of the treatment options; however, patients should know that some of these options do not have long term follow up which is critical," says Dr. Zaorsky, who conducted the research while at Thomas Jefferson. He is now at Fox Chase Cancer Center.

In the study, the researchers discuss how radiotherapy has changed considerably since the 1980s, when there were considerably less ways to deliver radiation. "But since then, we have figured out how to deliver very high doses of radiation very safely," Dr. Zaorsky says.

For prostate cancer, a standard of care today is dose-escalated conventionally fractionated external beam radiation therapy, in which the dose of X-ray radiation is delivered, once per day, five days per week, for up to eight weeks.

Nonetheless, the researchers found that studies have not yet shown that stereotactic body radiation therapy, high-dose brachytherapy, or proton beam therapy are more beneficial than the current standard of care.

"These treatments are very promising, but we haven't treated enough patients, or followed patients long enough, to definitively say these treatments should also be considered as good as, or better than, other standard therapies," Dr. Zaorsky says. "For example, the promise of proton beam therapy is that toxicity will be reduced, but this has not yet been shown for prostate cancer."

For these reasons, the researchers say that use of these newer radiotherapy techniques should be used within clinical trials, so that benefit and safety can be adequately assessed.

"We should personalize treatment for patients with prostate cancer. But at this point, we cannot tell patients that one approach will control cancer better than any other one," Dr. Zaorsky says.

The study was funded in part by the Kimmel Cancer Center's National Cancer Institute, Young Investigator Award from the Prostate Cancer Foundation to Robert B. Den, MD, the senior investigator of the study.

Researchers who participated in the study were Amy S. Harrison, MS, Edouard J. Trabulsi, MD, Leonard G. Gomella, MD, Mark D. Hurwitz, MD, Adam P. Dicker, MD, and Robert B. Den, MD, all from the Kimmel Cancer Center and Jefferson Medical College of Thomas Jefferson University; and Timothy N. Showalter, MD, from the University of Virginia.