Accuray (NSDQ:ARAY) today released data from two studies of its CyberKnife stereotactic body radiotherapy device exploring its use in treating patients with low and intermediate-risk prostate cancer, touting high survival rates and minimal toxicity.
The Sunnyvale, Calif.-based company touted the studies as the largest conducted to date evaluating stereotactic body radiation therapy in patients with localized prostate cancer. Results from the two studies were published in the International Journal of Radiation Oncology*Biology*Physics and in the journal European Urology Oncology.
“These multi-center studies reinforce the value the CyberKnife system can bring to a hospital’s prostate cancer treatment program and its potential to change the way the disease is treated by many physicians. The system enables clinical teams to achieve their treatment objectives, while providing a cost-effective, non-invasive option that is more convenient for patients. More than 20,000 prostate cancer patients have been treated with the CyberKnife system, clearly demonstrating the importance of these benefits to healthcare professionals and patients alike,” Accuray global medical and scientific affairs VP Fabienne Hirigoyenberry-Lanson said in prepared remarks.
Data from the multicenter studies indicated a 97% to 100% survival rate for low-risk patients and an 88% to 97% survival rate for intermediate-risk patients.
Results for low-risk patients were superior to the 92% to 94% survival rate indicated by historical data on conventional radiation therapy. Intermediate-risk patient survival rates were also higher than the 85% to 90% historical survival rates, Accuray said.
Accuray said that the survival rate among low-risk patients was equivalent to low dose rate brachytherapy and high dose rate brachytherapy without risks associated with the seed and catheter implants.
The company said that, despite the high dose delivered to the prostate, side effects were uncommon, with less than a 2% occurrence of grade 3 or higher toxicities, similar to other radiation therapy procedures without the need for rectal balloons or spacers.
“Our study treated over 300 prostate cancer patients across 21 centers throughout the United States. 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,” lead study investigator Dr. Robert Meier of Seattle’s Swedish Radiosurgery Center said in a press release.
“We evaluated an SBRT dosing regimen designed to emulate successful high dose rate brachytherapy plans and delivered in four visits. Study outcomes demonstrate that CyberKnife prostate SBRT is safe and effective for low- and intermediate-risk prostate cancer patients, producing a lower PSA nadir level than previously reported with other external radiotherapy techniques (< 0.1 ng/mL at 4 years and beyond), with minimal impact on quality of life during and after treatment. Of note, our treatment plans required steep dose fall-off from high-dose regions close to the bladder, urethra and rectum that would be difficult to deliver safely without the unique continual image-guidance and automatic correction of the beam aim made possible by the CyberKnife system,” study lead investigator Dr. Donald Fuller of San Diego’s Genesis Healthcare Partners said in a prepared statement.
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