Five-session prostate radiation linked to better bowel quality of life

For a patient facing prostate radiation, the difference can be counted on one hand or spread across several weeks: five SBRT sessions versus 20 or 28 IMRT sessions. In the Phase III NRG-GU005 trial, that shorter schedule was associated with better bowel health-related quality of life at two years among 698 evaluable patients with localized intermediate-risk prostate cancer.

Stereotactic body radiation therapy, or SBRT, delivers the study dose of 36.25 Gy in five fractions. The comparison treatments used moderately hypofractionated intensity-modulated radiation therapy, or IMRT, at 70 Gy in 28 fractions or 60 Gy in 20 fractions. The trial measured patients' own reports of bowel and urinary function, alongside disease-free survival.

The bowel result was concrete: 34.9% of patients receiving SBRT experienced a minimally clinically important decline in bowel quality of life, compared with 43.8% of those receiving IMRT. Longitudinal analyses also linked SBRT and the use of rectal spacers with improved bowel-domain scores. SBRT showed additional secondary benefits in lower incontinence-related quality-of-life impacts and better maintenance of erectile function.

The result was not a clean win. Urinary irritative and obstructive symptoms showed no significant difference: 33.7% of SBRT patients versus 34.7% of IMRT patients experienced a minimally clinically important change. The trial's quality-of-life co-primary endpoint was therefore not met, and its disease-free-survival analysis crossed a futility boundary for superiority because of higher biochemical failure, measured through prostate-specific antigen, in the SBRT arm.

So what changes in practice? For eligible patients and their care teams, the study supports a five-session option that may better preserve bowel quality of life than the tested IMRT schedules, while not proving superior urinary control or disease-free survival. The figures come from the NRG-GU005 trial, and Rodney J. Ellis of the University of South Florida said longer follow-up is warranted; the results do not establish SBRT as superior overall.