4 WEEK RADIOTHERAPY AS EFFECTIVE AS 8 WEEK IN PROSTATE CANCER

Hypofractionated radiotherapy was noninferior to standard radiotherapy in biochemical-clinical failure disease-free survival in men with localized prostate cancer, according to a study reported by Catton et al in the Journal of Clinical Oncology.

Study Details

In the trial, 1,206 patients with intermediate-risk prostate cancer from 27 centers in Canada, Australia, and France were randomized between May 2006 and November 2011 to receive hypofractionated radiotherapy consisting of 60 Gy in 20 fractions over 4 weeks (n = 608) or conventional radiotherapy consisting of 78 Gy in 39 fractions over 8 weeks (n = 598). Patients had to have T1 to 2a disease, Gleason score ≤ 6, and prostate-specific antigen (PSA) level of 10.1 to 20 ng/mL; T2b to 2c disease, Gleason score ≤ 6, and PSA level ≤ 20 ng/mL; or T1 to 2 disease, Gleason score = 7, and PSA level ≤ 20 ng/mL. No androgen-deprivation therapy was permitted.

The primary endpoint was biochemical-clinical failure defined by PSA failure (nadir + 2), hormonal intervention, clinical local or distant failure, or death as a result of prostate cancer. The noninferiority margin was 7.5% (hazard ratio [HR] < 1.32).

No Difference in Outcome

Median follow-up was 6.0 years. Biochemical-clinical failure occurred in 109 of 608 patients in the hypofractionated group vs 117 of 598 patients in the control group; 97 vs 100 events were PSA failures. The 5-year biochemical-clinical failure disease-free survival rate was 85% in both groups (HR = 0.96, 90% confidence interval = 0.77–1.2). Prostate cancer–related death occurred in 10 vs 12 patients.

Toxicity

Grade 3 acute genitourinary toxicity was observed in 3.9% vs 4.0% of patients; grade 3 late toxicity was observed in 2.0% vs 2.8%, and grade 4 late toxicity was reported in 0.2% vs 0.2%. Grade 3 acute gastrointestinal toxicity was observed in 0.7% vs 0.5%; grade 3 late toxicity was observed in 1.5% vs 2.7%, and grade 4 late toxicity was reported in 0% vs 0.2%.

The investigators concluded: “The hypofractionated [radiotherapy] regimen used in this trial was not inferior to conventional [radiotherapy] and was not associated with increased late toxicity. Hypofractionated [radiotherapy] is more convenient for patients and should be considered for intermediate-risk prostate cancer.”

The study was supported by the Canadian Institutes for Health Research.

Mark N. Levine, MD, of Ontario Clinical Oncology Group, Juravinski Hospital, Hamilton, Ontario, Canada, is the corresponding author of the Journal of Clinical Oncology article.