Five-treatment radiation therapy offers effective nonsurgical alternative for localized prostate cancer: Study

Five-treatment stereotactic body radiation therapy (SBRT) provided excellent long-term cancer control with fewer urinary and sexual side effects than surgery in the first randomized trial to directly compare the treatments for localized prostate cancer.

After a median follow-up of eight years, 91% of patients treated with SBRT remained free from biochemical or clinical failure, compared with 84% treated with surgery; the difference was not statistically significant. Together, the long-term cancer control and quality-of-life findings provide a more complete picture of the outcomes patients weigh when choosing treatment. Results will be presented today at the American Society for Radiation Oncology (ASTRO) Annual Meeting.

“Patients diagnosed with localized prostate cancer have long had to choose between surgery and radiation therapy without randomized evidence directly comparing the treatments. PACE-A changes that by providing long-term data on both cancer control and quality of life after surgery and SBRT,” said Nicholas van As, MD, principal investigator of the trial, a consultant clinical oncologist at The Royal Marsden NHS Foundation Trust and a professor at the Institute of Cancer Research in London. “Both treatments controlled the cancer extremely well, but SBRT offered clear advantages for urinary continence and sexual function.”

Prostate cancer that has not spread beyond the prostate may be managed with active surveillance or treated with surgery or radiation therapy. For patients who need treatment, the choice is often influenced by how each approach may affect urinary, bowel and sexual function.

SBRT uses advanced imaging and treatment planning to deliver the radiation dose directly to the prostate with pinpoint accuracy while limiting exposure to nearby healthy tissue in an effort to minimize side effects. Treatment is completed in five outpatient sessions over one to two weeks. Radical prostatectomy removes the prostate surgically, most commonly through a minimally invasive robotic procedure.

PACE-A is the first phase 3 randomized trial to directly compare SBRT with prostatectomy for localized prostate cancer. Earlier randomized studies comparing surgery with radiation therapy used conventionally fractionated treatment delivered over several weeks, rather than contemporary five-treatment SBRT.

The trial enrolled 123 patients at eight centers in the United Kingdom between 2012 and 2022. Most patients (94%) had low/intermediate-risk prostate cancer, and the median age was 65.5 years. Participants were randomly assigned to prostatectomy or five-treatment SBRT. Hormone therapy was not permitted.

Researchers assessed whether patients experienced biochemical or clinical failure, a composite measure that included rising prostate-specific antigen levels, recurrence, metastases, initiation of hormone therapy or death from prostate cancer.

Thirteen failures occurred during the follow-up period, including five patients treated with SBRT and eight treated with surgery. Five-year freedom from failure was 94% with SBRT and 95% with prostatectomy. At eight years, the rates were 91% and 84%, respectively. Neither difference was statistically significant. The trial was not designed to establish noninferiority for cancer control, however, so the results cannot determine whether the treatments were equivalent on this outcome.

“The numbers favor SBRT, but there were too few cancer events to conclude that it was superior,” Prof. van As said. “What we can say is that we saw very few cancer failures in either group, and that we have mature data showing excellent cancer outcomes with five-treatment radiotherapy.”

The high rates of cancer control after SBRT also align with findings from PACE-B, a larger randomized trial that compared SBRT with longer radiation schedules for patients with similar low- or intermediate-risk disease. That trial found SBRT noninferior to conventional radiation therapy, with 96% of patients failure-free at five years.

The PACE-A team previously reported less urinary incontinence and sexual dysfunction two years after SBRT compared with surgery, with slightly more bowel-related side effects. The new analysis extends these comparisons, finding that 8% of patients treated with SBRT reported using at least one urinary pad at five years, compared with 48% of those treated with surgery. Moderate or substantial bowel problems were uncommon in both groups.

Separate PACE-A results presented at ASTRO’s 2026 Annual Meeting also extend the sexual-function comparison through five years. Patient-reported sexual-function scores declined in both groups but remained significantly better after SBRT. At five years, median erectile-function scores on a 25-point scale, where higher scores indicate better function, were 19 after SBRT and 5 after prostatectomy.

“We now have longer-term information on both cancer control and the functional outcomes that matter greatly to patients,” Prof. van As said. “The urinary and sexual-function benefits seen at two years remained evident at five years, while cancer control remained excellent through longer follow-up. That gives patients a much fuller picture of what to expect from each treatment.”

The findings apply primarily to patients with favorable intermediate-risk prostate cancer. Patients with higher-risk disease often receive hormone therapy with radiation therapy and may require a different treatment approach. The PACE research program is continuing to evaluate SBRT in other prostate cancer settings, including with hormone therapy for higher-risk disease.

“In our practice, patients generally meet both a surgeon and a radiation oncologist, often in the same clinic,” he said. “That does not happen everywhere. Patients should know that surgery is not their only curative treatment option and have the opportunity to discuss the benefits and side effects of both approaches.”

Reference:

Five-treatment radiation therapy offers effective nonsurgical alternative for localized prostate cancer,American Society for Radiation Oncology, Meeting: American Society for Radiation Oncology Annual Meeting.