Five-Session SBRT Comparable to Conventional Radiotherapy in Localized Prostate Cancer Patients

Accuray Incorporated announced that results of the PACE-B – Prostate Advances in Comparative Evidence – trial were published in the New England Journal of Medicine. The research builds on previously reported data and shows that at five years, stereotactic body radiation therapy (SBRT) provides comparable rates of cancer control, tolerability and sexual functioning to conventional radiotherapy (CRT), while reducing the overall treatment timeframe from up to 39 days of treatment to just five days. The Accuray CyberKnife System was used in the SBRT treated arm of the PACE-B study and showed excellent disease control with low rates of toxicity for men with prostate cancer.

SBRT uses advanced techniques to deliver ultra-hypofractionated radiation therapy – very high doses of radiation are given over a few days – necessitating an extremely high degree of targeting accuracy and precision. The PACE-B trial enrolled men with low- or intermediate-risk prostate cancer who received SBRT in either five sessions or CRT in 20 or 39 sessions. 

Chief Investigator Professor Nicholas van As, Medical Director and Consultant Clinical Oncologist at The Royal Marsden NHS Foundation Trust, and Professor in Precision Prostate Radiotherapy at The Institute of Cancer Research, London, said, “At The Royal Marsden and the ICR, we are focused on developing smarter, better and kinder treatments for patients across the UK and internationally. Standard radiation treatment is already highly effective and is very well tolerated in people with localized prostate cancer but for a healthcare system and for patients, to have this treatment delivered just as effectively in five days as opposed to four weeks is hugely significant.

“To be able to sit with a patient and say, ‘We can treat you with a low toxicity treatment in five days, and your chance of keeping the cancer at bay for five years is 96 percent,’ is a very positive conversation to have. We expect our trial to be practice changing and people with intermediate risk prostate cancer should be given the option of SBRT as an alternative to conventional radiation or prostate surgery.”

Both groups attained high rates of cancer control at five years, with similar rates of 94.6 percent for CRT and 95.8 percent for SBRT achieved without the use of androgen deprivation therapy (ADT), also known as “hormone therapy.” SBRT was well-tolerated and treatment-related impairment (such as urinary, bowel and sexual function) and bother were comparable to CRT.

“Bother” refers to the annoyance that patients experience because of a decline in their ability to perform certain functions. At five years, 29.1 percent of men treated with CRT and 26.4 percent of men receiving SBRT reported erectile dysfunction, while participants in both groups stated they had stable urinary and bowel symptoms at this time point.

"As a radiation oncologist who has had the privilege of treating numerous men with prostate cancer, I am grateful that the medical community continues to invest resources into refining our approach to this common diagnosis. The results of the PACE-B trial are published in one of the premier medical journals and are a game-changer. They provide the most compelling level of data to date in support of prostate SBRT for early-stage disease, and directly inform the standard of care. This trial empowers men who require or prefer radiation treatment to utilize SBRT, a technique that not only offers highly effective cancer therapy, but also significantly reduces the disruption to their lives compared to traditional schedules. This trial represents a crucial step forward in improving medical care and enhancing the quality of life for men diagnosed with prostate cancer," said Seth Blacksburg, MD, MBA, Chief Medical Officer at Accuray. 

Continued Dr. Blacksburg, “The CyberKnife System is supported by more than 30 years of global clinical data, including the results from the PACE-B trial. The system equips medical care teams to treat prostate cancer with tremendous confidence, assuring them of a tool that consistently delivers extremely accurate treatments. This reliability not only enhances the likelihood of successful outcomes but also minimizes potential side effects, providing an optimal approach to curing this common medical condition.”

The prostate gland can move unpredictably and rapidly throughout the treatment, sometimes moving as much as 10 mm in as little as 30 seconds due to normal patient bodily functions. The ability to track, detect and correct for this motion is key to ensuring the radiation is delivered to the tumor. 

Throughout the course of treatment, the CyberKnife System continually collects images to determine exactly where the tumor is, helping to ensure that clinicians deliver radiation exactly where they want it. The system detects the tumor motion and automatically adjusts the radiation beam in real time to match the motion of the tumor, giving clinicians confidence to apply smaller treatment margins and enabling higher doses and fewer treatments. The CyberKnife System is the only radiotherapy device that can track and automatically correct for prostate motion and maintain sub-millimeter accuracy throughout treatment delivery.