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The optimal radiation dose fractionation schedule for localized prostate cancer is unclear. This study was designed to compare two dose fractionation schemes (a shorter 4-week radiation schedule v a longer 6.5-week schedule).

Patients with early-stage (T1 or T2) prostate cancer were randomly assigned to 66 Gy in 33 fractions over 45 days (long arm) or 52.5 Gy in 20 fractions over 28 days (short arm). The study was designed as a noninferiority investigation with a predefined tolerance of −7.5%. The primary outcome was a composite of biochemical or clinical failure (BCF). Secondary outcomes included presence of tumor on prostate biopsy at 2 years, survival, and toxicity.

From March 1995 to December 1998, 936 men were randomly assigned to treatment; 470 were assigned to the long arm, and 466 were assigned to the short arm …