In men with low-risk prostate cancer, radiotherapy with 70 Gy in 28 fractions over 5.6 weeks is non-inferior to 73.8 Gy in 41 fractions over 8.2 weeks, a study presented at the 2016 Genitourinary Cancers Symposium has shown.1
For the phase 3 trial, researchers sought to assess whether the efficacy of a hypofractionated radiotherapy schedule is no worse than a conventional schedule in patients with low-risk prostate cancer. Researchers enrolled a total of 1115 men with T1-2a disease, a Gleason score of 6 or less, and a prostate-specific antigen level less than 10.
Of those, 1101 participants were randomly assigned 1:1 to receive a conventional schedule consisting of 73.8 Gy in 41 fractions over 8.2 weeks or a hypofractionated schedule consisting of 70 Gy in 28 fractions over 5.6 weeks.
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Results showed that at a median follow-up of 5.9 years, the estimated 7-year disease-free survival was 75.6% (95% CI, 70.3 – 80.1) in the conventional arm and 81.8% (95% CI, 77.5 – 85.3) in the hypofractionated arm (HR, 0.85; 95% CI, 0.64 – 1.14), suggesting non-inferiority between the 2 arms.
Researchers also found that a hypofractionated schedule is non-inferior to a conventional schedule in terms of overall survival (HR, 0.95; 95% CI, 0.65 – 1.41) and biochemical recurrence (HR, 0.77; 95% CI, 0.51 – 1.17).
In regard to safety, grade 3 or higher gastrointestinal toxicity occurred in 3.0% of patients in the conventional arm compared with 4.6% of patients in the hypofractionated arm (RR, 1.53; 95% CI, 0.86 – 2.83). For grade 3 or higher genitourinary toxicity, the rates were 4.5% and 6.4%, respectively (RR, 1.43; 95% CI, 0.86 – 2.37).
Reference
- Lee WR, Dignam JJ, Amin M, et al. NRG Oncology RTOG 0415: A randomized phase III non-inferiority study comparing two fractionation schedules in patients with low-risk prostate cancer. J Clin Oncol. 2016; 34 (suppl 2S; abstr 1).
