Accuray Incorporated has announced that data from a prospective, 21 center study showed 97 percent of low- and intermediate-risk prostate cancer patients had excellent cancer control five years after receiving stereotactic body radiation therapy (SBRT) administered with the CyberKnife® System. The treatment was extremely well-tolerated; serious side effects were uncommon (less than two percent) after more than five years of follow-up. The study was presented during an oral session at the American Society for Radiation Oncology (ASTRO) 58th Annual Meeting.

SBRT is a treatment process necessitating an extremely high degree of precision. It offers a much shorter course of treatment for prostate cancer patients than conventional radiation and is noninvasive (no conventional surgery involved). SBRT is cost-effective for healthcare providers and payers, and also increases patient satisfaction by reducing discomfort and scheduling inconvenience versus conventional radiation treatments.

"For men with newly diagnosed prostate cancer, this study changes the game. SBRT provided better cancer control with few side effects, and required only 5 short treatments, without the need for surgery." said Robert M. Meier, MD, medical director of the Swedish Cancer Institute at Northwest Hospital in Seattle, Washington and lead investigator of the study. "The CyberKnife System's real-time image guidance, non-coplanar beam delivery, and sub-millimeter accuracy enabled clinicians across multiple centers to achieve consistent, excellent dose control, with reduced toxicities compared to other radiotherapies."

The study titled, "Five-Year Outcomes from a Multi-Center Trial of Stereotactic Body Radiotherapy for Low- and Intermediate-Risk Prostate Cancer," is the first large, multi-center clinical trial with long-term follow-up and good quality assurance to evaluate the use of SBRT in prostate cancer delivered by the CyberKnife System. It demonstrated that:

  • Five-year recurrence-free survival rates were almost identical for low- and intermediate-risk patients;
  • In low-risk prostate cancer patients the five-year cancer control rate (97.3 percent) was superior to historical external beam radiation therapy control rates (93 percent);
  • Dose-escalated prostate CyberKnife SBRT can be safely administered across multiple institutions, reinforcing the feasibility of the treatment methodology;
  • Toxicity rates compare favorably to other radiotherapies, based on results from other studies.

The prostate gland can move unpredictably throughout the course of treatment because of normal patient bodily functions. This makes it vitally important to be able to track, detect and correct for all types of motion. Unlike any other radiation treatment, the CyberKnife® System continually tracks and automatically corrects the beam for movement of the prostate in real-time throughout the entire treatment session. With this automatic motion-tracking and adjustment, the CyberKnife® System's accuracy is sub-millimeter - its pinpoint precision is within the thickness of a dime, enhancing clinicians' ability to treat effectively while preserving healthy tissue.

"This most recent research demonstrates clearly why the CyberKnife System has become the radiation therapy system of choice for many clinicians and their patients when evaluating treatment options for prostate cancer," said Fabienne Hirigoyenberry-Lanson, PhD, vice president global clinical development, at Accuray. "The System is uniquely positioned to play an important role in delivering on the far-reaching priorities of health systems worldwide seeking to improve patient outcomes and reduce costs."

About the Study

The study was designed to assess whether dose-escalated stereotactic body radiation therapy (SBRT) could be effectively and safely administered across multiple community, regional and academic institutions. Additionally, the study evaluated whether, in low-risk patients, dose escalation would improve five-year disease-free survival rates compared to historic controls. Study participants included 309 evaluable patients, 172 low-risk and 137 intermediate-risk. All patients were treated with a non-coplanar robotic SBRT platform, the CyberKnife System, using real-time tracking of implanted fiducials.