New study led by Swedish shows effectiveness of prostate cancer therapy with CyberKnife

November 09, 2018

Results from a recent national research study proves many prostate cancer patients can be effectively treated in a five-day treatment course using CyberKnife. The study, led by principle investigator Robert M. Meier, MD, medical director of the Swedish Radiosurgery, published online this month in the International Journal of Radiation Oncology*Biology*Physics.

The trial represents the largest multi-institutional prospective study of CyberKnife to treat localized prostate cancer. Researchers at 21 medical centers, including Swedish, followed the clinical outcomes of 309 prostate cancer patients, 172 with low-risk and 137 with intermediate risk cancer, for five years after CyberKnife treatment. The observational study specifically followed low- and intermediate-risk patients, which comprise the majority of all prostate cancer patients in the U.S.

Results from the study showed that intermediate-risk prostate cancer patients treated with CyberKnife had a disease-free survival rate of 97.1 percent five years after treatment. For low-risk prostate cancer patients treated with CyberKnife, the five-year disease-free survival rate was 97.3 percent. Patient outcomes were not compared against a study control group, but rather were analyzed against data from earlier research involving other radiation therapy methods.

“The CyberKnife’s unique architecture tracks and automatically corrects for prostate motion, delivering radiation with sub-millimeter accuracy. This exceptional precision allowed us to give a more effective dose of radiotherapy, which translated into superior cancer control. Since we were able to avoid the healthy tissues which lie immediately adjacent to the prostate, side effects were uncommon,” said Dr. Meier.

In addition to showing exceptional cancer control, the study results demonstrated that CyberKnife treatment is also well-tolerated, with less than two percent of patients reporting significant side effects from treatment. The side effects from CyberKnife were favorable when compared to historical controls involving conventional radiation therapy and surgery, which have rates of significant side effects up to four percent. 

“The study affirms that CyberKnife treatment is a very compelling, cost-effective, non-invasive option for men with low- and intermediate-risk prostate cancer,” said Dr. Daniel Landis, a longtime radiation oncologist with extensive experience in the treatment of prostate cancer at the Swedish Cancer Institute.

CyberKnife administers high doses of radiation, using several beams of various intensities aimed at different angles to precisely target the tumor. One or more sessions of treatment planning with CT, MRI or other advanced imaging techniques are used to precisely map the position of the prostate. The images are then used to design a four-dimensional, customized treatment plan that determines beam intensity and positioning. The goal is to deliver the highest possible dose to kill the cancer while minimizing exposure to healthy organs.

These treatments are usually given over five daily treatments, although this can vary depending on the type and location of the tumor and the patient’s physical condition.

Learn more about the Swedish prostate cancer treatment program at www.swedish.org/cyberknifeprostate or call (206) 320-7187.

*The study was recently published online in the International Journal of Radiation Oncology*Biology*Physics and in the European Urology Oncology. It is also in the October print edition of the Red Journal, the official publication of the American Society for Radiation Oncology (ASTRO).