SBRT Noninferior to Conventional RT in Prostate Cancer

TOPLINE: 

Five-fraction stereotactic body radiotherapy (SBRT) was found to be noninferior to conventionally or moderately hypofractionated radiotherapy in treating localized prostate cancer, with a 5-year freedom from biochemical or clinical failure rate of 95.8% vs 94.6%. A downside to SBRT was that it was associated with a higher incidence of late genitourinary toxic effects.

METHODOLOGY:

• Radiotherapy is considered curative for the majority of patients with localized prostate cancer. Hypofractionation, involving higher doses of radiotherapy per treatment session, has the potential to maintain treatment efficacy while reducing the total number of sessions, and moderate hypofractionation is a standard of care. SBRT allows “ultrahypofractionated radiotherapy to be delivered with precision,” the authors wrote.
• In the new study, researchers conducted a phase 3, international, open-label, randomized controlled trial involving 874 men with localized prostate cancer.
• Participants were randomly assigned to receive either SBRT (36.25 Gy in five fractions over 1-2 weeks) or control radiotherapy (78 Gy in 39 fractions over 7.5 weeks or 62 Gy in 20 fractions over 4 weeks).
• The primary endpoint was freedom from biochemical or clinical failure, with a critical hazard ratio for noninferiority of 1.45.
• The trial was conducted across 38 centers in the United Kingdom, Ireland, and Canada, with a median follow-up of 74 months.

TAKEAWAY:

• SBRT was found to be noninferior to conventional radiotherapy, with a 5-year freedom from biochemical or clinical failure rate of 95.8% vs 94.6% (P = .004 for noninferiority).
• The cumulative incidence of late Radiation Therapy Oncology Group (RTOG) grade 2 or higher genitourinary toxic effects at 5 years was higher with SBRT (26.9%) than with control radiotherapy (18.3%) (P
• No significant difference was observed in the cumulative incidence of late RTOG grade 2 or higher gastrointestinal toxic effects between SBRT (10.7%) and control radiotherapy (10.2%) (P = .94).
• The incidence of Common Terminology Criteria for Adverse Events grade 2 or higher erectile dysfunction at 5 years was similar between SBRT (26.4%) and control radiotherapy (29.1%) (P = .46).

IN PRACTICE: 

The findings “show that five-fraction SBRT is a robust and viable alternative to moderately fractionated radiotherapy for prostate cancer, offering equivalent efficacy with enhanced convenience for patients. The high 5-year incidence of biochemical control and the acceptable side-effect profile, coupled with the considerable advancements in radiotherapy delivery, underscore the potential of the use of SBRT in prostate cancer treatment,” the authors of the study wrote. 

SOURCE:

This study was led by Nicholas van As, MD, The Royal Marsden Hospital in London, England. It was published online on October 16 in The New England Journal of Medicine.

LIMITATIONS:

The study’s limitations included the exclusion of patients with high-risk prostate cancer and that androgen-deprivation therapy was not permitted, which may have limited the generalizability of the findings. Additionally, the open-label design could have introduced bias in the reporting of outcomes.

DISCLOSURES:

The study was supported by funding from Accuray to The Royal Marsden NHS Foundation Trust for trial management, international study coordination, and data analysis. Additional disclosures are noted in the original article.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.