Multinational phase 3 trial of stereotactic body radiotherapy for localized prostate cancer

Whether stereotactic body radiotherapy (SBRT) is noninferior to conventionally or moderately hypofractionated radiotherapy (RT) regimens with respect to biochemical or clinical failure in patients with localized prostate cancer is unclear. The phase 3 PACE-B trial, at 38 centers in the UK, Ireland, and Canada randomized patients with T1 or T2 low-risk or intermediate risk prostate cancer to five-fraction SBRT or control RT. At a median follow-up of 74.0 months, the 5-year incidence of freedom from biochemical or clinical failure was 95.8% with SBRT versus 94.6% with control RT (p for noninferiority 0.004). The 5-year incidence of grade 2 or higher GU toxic effects was 26.9% with SBRT and 18.3% with control RT; the 5-year incidence of grade 2 or higher GI toxic effects was 10.7% with SBRT and 10.2% with control RT (p=0.94). The authors conclude that five-fraction SBRT was noninferior to control RT with respect to biochemical or clinical failure and may be an efficacious treatment option for patients with low-to-intermediate risk localized prostate cancer.