onc brain

Phase 3 international randomised trial, 1:1 central allocation by ICR-CTSU with permuted blocks, stratified by centre and NCCN risk group. Treatment allocation was open-label. Of 874 randomised, 844 formed the analysis population (SBRT=414, CRT=430), median follow-up 85.7 and 85.6 mo.

Men with low-/intermediate-risk localised prostate cancer. Baseline characteristics balanced; baseline PROM data pooled across arms given equivalent pretreatment function.

SBRT 36.25 Gy in five fractions versus CRT 78 Gy in 39 fractions or 62 Gy in 20 fractions. Image-guidance method was not analysed as a variable, and rectal spacer use is not reported in this analysis.

Primary comparison: SBRT vs CRT at 5 yr for each PROM endpoint, using EPIC-26 urinary incontinence, sexual and bowel domains plus the Vaizey faecal incontinence score at baseline, 1, 2 and 5 yr. Binary outcomes by chi-squared with Wilson 95% CIs; continuous by Mann-Whitney.

All predefined between-group differences were nonsignificant. Sexual domain median score fell from 48.7 (IQR 22.2-77.8) to 26.3 (IQR 16.7-57) for SBRT and 54.2 (IQR 27.8-75.0) to 24.3 (IQR 16.7-52.8) for CRT, p=0.89.

Moderate or big urinary leakage problems reached 6% (15/250) SBRT and 4% (9/244) CRT; bowel problems 5% in both arms. Solid stool incontinence never/rarely in 94% (232/248) SBRT and 90% (217/241) CRT; liquid stool 92% in both.

PACE-B previously showed SBRT non-inferior to conventional and moderately hypofractionated RT for efficacy but with higher cumulative GU adverse events; these PROMs argue that excess did not persist to 5 yr. Against TrueNTH's robotic prostatectomy benchmark at 1 yr (42% leak- and pad-free, 6% of baseline-potent men retaining intercourse-adequate erections), the RT curves sit far better, and PACE-A reported pad use of 4.6% after SBRT versus 46.9% after prostatectomy.

The EPIC-26 irritative/obstructive domain was not included, removing the symptom cluster most often attributed to SBRT, though the authors note no 5-yr difference was seen in prior reporting. There is no untreated control arm, so age-related decline is unseparated from treatment effect, and no analysis by image-guidance method.

The clinically useful claim is narrow and real: five fractions buys convenience without a late functional cost relative to 20 or 39 fractions. The cross-modality framing against surgery is the weaker half, comparing separate cohorts at different timepoints with a shared instrument rather than a randomised contrast.

Prespecified 5-yr PROM analysis of a phase 3 RCT; all between-group differences nonsignificant, supporting five-fraction SBRT already in guideline use. Attrition to ~60% limits precision.