November 14, 2013 — Accuray Inc. announced the publication of two papers stemming from a large multi-center study of CyberKnife stereotactic body radiotherapy (SBRT) led by investigators at the University of California, Los Angeles (UCLA).
The first paper, published in the September 2013 online issue of Radiotherapy & Oncology (commonly referred to as the Green Journal), found, in more than 1,000 patients with organ-confined prostate cancer, relapse-free survival rates were comparable to other established treatments at both three- and five-year intervals post-treatment. The second paper published in the October 10 issue of the International Journal of Radiation Oncology (commonly referred to as the Red Journal) demonstrated that CyberKnife SBRT (stereotactic body radiation therapy) was a well-tolerated treatment that allowed patients to return to their pre-treatment health-related quality of life (QoL).
“These studies confirm with a much larger patient population and longer follow-up what many smaller studies have already suggested: SBRT is an effective method for treating prostate cancer,” said Christopher King, Ph.D., M.D., professor of radiation oncology and urology, UCLA School of Medicine and lead author of the study. “Compact dose delivery and real-time tracking of prostate motion gave the authors of these studies the confidence to explore the potential of high-dose, extreme hypofractionation. Clinical outcomes so far validate the effectiveness and safety of treating patients with prostate cancer with minimal disruption to their lives.”
In the first paper from the study published in the Green Journal, titled, “Stereotactic body radiotherapy for localized prostate cancer: Pooled analysis from a multi-institutional consortium of prospective phase II trials,” 1,100 patients with low-, intermediate- or high-risk prostate cancer were treated with the CyberKnife System and followed for a median of 36 months. Relapse-free survival rates were comparable to or better than other established treatments at both three- and five-year intervals post-treatment. Additionally, for the 135 patients with at least five years follow-up, disease-free survival was 99 percent for low-risk and 93 percent for intermediate-risk patients.
In the second paper, “Health related quality of life after stereotactic body radiotherapy for localized prostate cancer,” published in the Red Journal, health-related QoL was assessed in 864 patients after prostate SBRT on the CyberKnife System. Reductions in urinary and bowel QoL recovered to baseline levels or better within six months and remained so over the long term. Sexual QoL declined in the first nine months in a manner that was no worse than that seen with other modern approaches to radiation therapy and observed in other studies. Overall, the QoL outcomes compared favorably to surgery and other kinds of radiotherapy.
The CyberKnife is equipped with the InTempo Adaptive Imaging System, which enables real-time tracking and correcting of the prostate during treatment. This image-guidance technology ensures the CyberKnife is on target, sparing normal tissue despite unpredictable, sometimes extensive prostate movement.