Five-Session Radiation Matches Surgery in Long-Term Prostate Cancer Control Trial

Men diagnosed with localized prostate cancer have long faced one of the most consequential decisions in oncology: undergo surgery to remove the prostate, or commit to a course of radiation therapy, with little rigorous evidence to tell them how the two options truly compare. Now, for the first time, a randomized phase 3 trial has directly pitted modern five-treatment stereotactic body radiation therapy against radical prostatectomy, and the long-term results suggest that the shorter radiation course holds its own against surgery while sparing patients some of the most feared side effects of treatment. The findings, presented at the American Society for Radiation Oncology Annual Meeting in Boston, offer what researchers describe as a much fuller picture of the trade-offs patients face when choosing a curative therapy.

The trial, known as PACE-A, enrolled 123 patients at eight centers in the United Kingdom between 2012 and 2022. Most participants, 94 percent, had low- or intermediate-risk disease, and the median age was 65.5 years. Patients were randomly assigned to either surgical removal of the prostate, most commonly performed as a minimally invasive robotic procedure, or to stereotactic body radiation therapy, a technique that delivers the entire radiation dose in just five outpatient sessions spread over one to two weeks. Notably, hormone therapy was not permitted in either arm, isolating the comparison between the two local treatments themselves. After a median follow-up of eight years, the researchers found that 91 percent of men treated with radiation remained free from biochemical or clinical failure, compared with 84 percent of those treated with surgery, a difference that did not reach statistical significance.

The composite endpoint used in the trial captured the outcomes that matter most in prostate cancer follow-up: rising prostate-specific antigen levels, evidence of recurrence, the development of metastases, the initiation of hormone therapy, or death from prostate cancer. In total, thirteen failure events occurred during the follow-up period, five among men who received radiation and eight among those who underwent surgery. At the five-year mark, freedom from failure was 94 percent in the radiation group and 95 percent in the surgery group, nearly identical figures that underscore how effective both modalities are at controlling disease confined to the prostate. The investigators were careful to note, however, that the trial was not designed or powered to establish noninferiority for cancer control, so the results cannot formally declare the two treatments equivalent on this measure.

Principal investigator Nicholas van As, a consultant clinical oncologist at The Royal Marsden NHS Foundation Trust and a professor at the Institute of Cancer Research in London, emphasized that the small number of events limits what can be concluded about relative efficacy. The numbers numerically favored radiation, he explained, but there were too few cancer events to claim superiority. What the data do establish, he argued, is that very few cancer failures occurred in either group and that mature, long-term evidence now supports excellent outcomes with five-treatment radiotherapy. For a field in which earlier randomized comparisons of surgery and radiation relied on conventionally fractionated radiation delivered over several weeks, the use of contemporary stereotactic technique makes these findings particularly relevant to current practice.

The cancer control results also align closely with those of PACE-B, a larger randomized trial that compared five-treatment stereotactic radiation with longer conventional radiation schedules in patients with similar low- or intermediate-risk disease. That study found the abbreviated approach noninferior to conventional fractionation, with 96 percent of patients failure-free at five years. Taken together, the two trials suggest that compressing a curative course of radiation into a single week does not compromise the ability to eradicate localized disease, a conclusion that has already begun to reshape how radiation oncologists counsel patients about treatment duration and convenience.

Perhaps the most striking findings concern quality of life, an outcome that weighs heavily in treatment decisions because both surgery and radiation can affect urinary, bowel, and sexual function. The PACE-A team had previously reported, at the two-year mark, less urinary incontinence and sexual dysfunction after radiation compared with surgery, along with slightly more bowel-related side effects. The new analysis extends those comparisons to five years and reveals a substantial and persistent gap in urinary outcomes: 8 percent of men treated with radiation reported using at least one urinary pad at five years, compared with 48 percent of those treated with surgery. Moderate or substantial bowel problems, meanwhile, remained uncommon in both groups, suggesting that the modest bowel trade-off seen earlier did not translate into a major burden over time.

Sexual function followed a similar pattern. Patient-reported scores declined in both groups over the follow-up period, an expected consequence of any curative prostate treatment, but they remained significantly better after radiation. At five years, the median erectile-function score on a 25-point scale, where higher scores indicate better function, was 19 among men treated with radiation compared with 5 among those who underwent prostatectomy. Van As noted that the urinary and sexual-function benefits observed at two years remained evident at five years, while cancer control stayed excellent through longer follow-up, giving patients a far more complete picture of what to expect from each approach than was previously available.

The findings apply primarily to patients with favorable intermediate-risk disease, the population enrolled in the trial. Men with higher-risk prostate cancer often receive hormone therapy in combination with radiation and may require a different treatment strategy altogether, so these results should not be extrapolated beyond the studied group. The PACE research program continues to evaluate stereotactic radiation in other prostate cancer settings, including its use alongside hormone therapy for higher-risk disease, work that may eventually broaden the pool of patients who can benefit from the abbreviated schedule.

For clinicians, the trial highlights the importance of multidisciplinary counseling. Van As described a practice model in which patients generally meet both a surgeon and a radiation oncologist, often in the same clinic, an arrangement he acknowledged does not exist everywhere. His message to patients is direct: surgery is not the only curative option, and every man facing a new diagnosis of localized prostate cancer deserves the opportunity to discuss the benefits and side effects of both approaches before committing to one. Amar U. Kishan, chair of the ASTRO Genitourinary Cancer Resource Panel and a radiation oncologist at UCLA, echoed that framing, noting that the trial followed patients long enough to address both the durability of cancer control and its impact on daily life, showing durable control with both approaches and persistently better sexual and urinary function after five-treatment radiation.

The significance of PACE-A extends beyond its headline numbers. By providing the first randomized long-term comparison between robotic prostatectomy and contemporary five-session stereotactic radiation, the trial fills an evidence gap that has persisted for decades, one that left patients to choose between treatments based largely on retrospective data and physician preference. With 91 percent freedom from failure at eight years after radiation, pad use roughly six times less common than after surgery, and erectile-function scores nearly four times higher at five years, the data give radiation therapy a stronger claim as a first-line nonsurgical alternative. As the PACE program continues to mature and expand into higher-risk settings, the weeklong radiation course may increasingly become a default consideration in clinics where both options are offered side by side.

Subject of Research: Randomized comparison of stereotactic body radiation therapy versus radical prostatectomy for localized prostate cancer

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

Article References: Five-treatment radiation therapy offers effective nonsurgical alternative for localized prostate cancer. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: prostate cancer, SBRT, radiation therapy, prostatectomy, PACE-A trial, ASTRO, urinary continence, erectile function, randomized trial, cancer control, quality of life, The Royal Marsden