Study: Shorter radiation schedule matches safety of standard prostate cancer treatment

Editor's Note

New research shows postoperative prostate cancer radiation delivered via stereotactic body radiotherapy (SBRT)—which includes just five high-dose sessions—appears as safe and tolerable as weeks-long conventional treatment. Medical Xpress reported on the findings May 15.

Led by by UCLA’s Jonsson Comprehensive Cancer Center and published in JAMA Oncology, the SCIMITAR phase II trial assessed the safety and feasibility of SBRT following prostatectomy. Although already established for patients who have not undergone surgery, postoperative use of this technique had bene limited by concerns over targeting accuracy due to organ movement, Medical Xpress reports. With advances in MRI-guided radiation and image-based motion tracking, the trial set out to reevaluate those limitations. 

To that end, researchers tracked outcomes in 100 men who received SBRT after surgery and compared them with 200 men who received standard radiation. Over two years, SBRT patients reported similar rates of urinary and bowel side effects as their conventionally treated counterparts—25% had moderate urinary issues, 4% had severe urinary symptoms, and just 3% reported moderate or severe bowel problems, Medical Xpress reports. Quality-of-life outcomes were also equivalent between the two groups throughout the follow-up period.

Importantly, the outlet reports that the MRI-guided SBRT subgroup experienced fewer late genitourinary and gastrointestinal side effects. Researchers credited this to more precise targeting using narrower treatment margins (3mm vs. 5mm), made possible by improved imaging and real-time motion management.

While the SCIMITAR trial focused primarily on safety and patient-reported outcomes, the article notes that longer-term follow-up will be required to assess SBRT’s effectiveness in cancer control. A separate trial, EXCALIBUR, is underway to evaluate long-term results. An update from SCIMITAR on cancer recurrence rates is expected later this year.