BOSTON — Stereotactic body radiotherapy (SBRT) and radical prostatectomy provide comparable long-term control of localized prostate cancer, but radiotherapy comes with far fewer urinary and sexual problems, according to the first phase 3 randomized trial to directly compare the two options.

Based on results from 123 UK men randomly assigned to either approach in the PACE-A trial, the 8-year Kaplan-Meier estimate of freedom from biochemical or clinical failure was 91% with SBRT and 84% with prostatectomy. The difference was not statistically significant.

There were substantial differences, however, in long-term side effects, according to findings presented at the American Society for Radiation Oncology (ASTRO) 2026 Annual Meeting in Boston.

At 5 years, nearly half of surgery patients (48%) reported using at least one urinary pad per day for incontinence compared with only 8% of men treated with SBRT. Similarly, those who received radiotherapy had a median score of 19 on a 25-point erectile function scale, while surgery patients had a median score of 5 — the lowest possible on the scale.

“Patients diagnosed with localized prostate cancer have long had to choose between surgery and radiation therapy without randomized evidence directly comparing the treatments,” said principal investigator Nicholas van As, MD, an SBRT specialist at The Royal Marsden in London, England. “PACE-A changes that,” he noted.

While both approaches were highly effective, he said, SBRT “offered clear advantages” for urinary continence and sexual function.

“I’m very confident in the outcomes,” van As added.

Amar Kishan, MD, a genitourinary radiation oncologist at the University of California, Los Angeles, agreed.

“Patients choosing treatment for localized prostate cancer want to know how well it will control their cancer and how it may affect their daily lives,” Kishan said. “Together, these longer-term data give patients a more complete picture of what they can expect from each treatment.”

Men in PACE-A were treated at eight centers in the UK between 2012 and 2022. Most had intermediate-risk disease, while just less than 6% had low-risk; their median age was 65.5 years.

Sixty patients were randomly assigned to prostatectomy and 63 to SBRT, which was delivered at 36.25 Gy in five fractions over 1-2 weeks. The large majority of prostatectomies were robotic, and the rest were laparoscopic.

There was no further treatment until men hit the trial’s endpoint of biochemical or clinical failure, which was a composite measure of rising prostate-specific antigen levels, recurrence, metastases, initiation of hormone therapy, or death from prostate cancer.

At a median of 8 years, there were five failures in the SBRT arm and eight in the surgery group.

“The numbers favor SBRT,” van As said, “but there were too few cancer events to conclude that it was superior. What we can say is that we saw very few cancer failures in either group.”

At 5 years, just one prostatectomy patient and no one in the radiation group reported bowel function problems.

Van As noted that the PACE research program is continuing to evaluate SBRT in other prostate cancer settings, including with upfront hormone therapy for men with higher-risk disease.

The work was funded by Varian and Accuray; van As disclosed research funding from both. Kishan reported having numerous industry ties, including to Boston Scientific and Janssen. 

M. Alexander Otto is a physician assistant and award-winning journalist. He is also an MIT science journalism fellow. Email: aotto@medscape.net.