• Felix Leborgne, Jack Fowler, José H Leborgne, and Julieta Mezzera.
• Department of Radiation Oncology, Hospital Italiano, Montevideo, Uruguay.
• Int. J. Radiat. Oncol. Biol. Phys. 2012 Mar 1; 82 (3): 1200-7.

PurposeNow that the follow-up time has exceeded 5 years, an estimate of the α/β ratio can be presented. The additional late outcomes in patients treated with three-dimensional conformal external beam radiotherapy for localized prostate cancer using a hypofractionated vs. a standard fractionation regimen are reported from this prospective nonrandomized contemporary comparison.Methods And MaterialsA total of 114 nonrandomized patients chose hypofractionation delivered in 20 fractions of 3 Gy or 3.15 Gy (mean 3.06 Gy) for localized prostate cancer within a median overall time of 32 days (range, 29-49) using four fractions weekly. A total of 160 comparable patients were contemporarily treated within a median of 55 days (range 49-66). The median follow-up was 66 months (range, 24-95) for the hypofractionated arm and 63 months (range, 36-92) for the standard arm. The percentage of patients in the low-, medium-, and high-risk groups was 36%, 46%, and 18% in the hypofractionated arm and 44%, 50%, and 6% in standard arm (2 Gy), respectively.ResultsThe 5-year actuarial biochemical absence of disease (prostate-specific antigen nadir + 2 ng/mL) and disease-free survival rate was the same at 89% in both arms, making the α/β calculation unambiguous. The point ratio of α/β was 1.86 (95% confidence interval, 0.7-5.1 Gy). The 95% confidence interval was determined entirely by the binomial confidence limits in the numbers of patients. Rectal reactions of grade 3 and 4 occurred in 1 of 114 (hypofractionated) and 2 of 160 (standard) patients.ConclusionsThe presented three-dimensional conformal regimen was acceptable, and the α/β value was 1.8, in agreement with other very recent low meta-analyses (reviewed in the "Discussion" section).Copyright © 2012 Elsevier Inc. All rights reserved.

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