As reported in the Journal of Clinical Oncology by W. Robert Lee, MD, MS, and colleagues, a 12-year analysis of the phase III NRG Oncology RTOG 0415 trial has shown continued noninferiority in terms of disease-free survival with hypofractionated radiotherapy vs conventionally fractionated radiotherapy in patients with low-risk prostate cancer.
A prior report from the trial—a median follow-up of 5.8 years—showed noninferiority of hypofractionated radiotherapy vs conventionally fractionated radiotherapy.
![W. Robert Lee, MD, MS](/media/1473/62122_lee.jpg)
W. Robert Lee, MD, MS
Study Details
In the noninferiority trial, 1,092 patients were randomly assigned to receive hypofractionated radiotherapy with 70 Gy in 28 fractions (n = 550) or conventionally fractionated radiotherapy with 73.8 Gy in 41 fractions. Radiotherapy was delivered as 3D or intensity-modulated treatment, with the latter used in 79% of patients. Androgen-deprivation therapy was not permitted. The primary endpoint of the trial was disease-free survival.
Key Findings
Median follow-up in the current analysis was 12.8 years. Disease-free survival rates at 12 years were 61.8% (95% confidence interval [CI] = 57.2%–66.0%) in the hypofractionated radiotherapy group vs 56.1% (95% CI = 51.5%–60.5%) in the conventionally fractionated radiotherapy group (hazard ratio [HR] = 0.85, 95% CI = 0.71–1.03), confirming noninferiority of hypofractionated radiotherapy (P < .001 for noninferiority).
The 12-year cumulative incidence of biochemical failure was 9.9% (95% CI = 7.5%–12.6%) in the hypofractionated radiotherapy group vs 17.0% (95% CI = 13.8%–20.5%) in the conventionally fractionated radiotherapy group (HR = 0.55, 95% CI = 0.39–0.78).
Overall survival at 12 years was 69.9% (95% CI = 65.5%-73.9%) in the hypofractionated radiotherapy group vs 68.7% (95% CI = 64.3%–72.7%) in the conventionally fractionated radiotherapy group.
Overall, late grade ≥ 3 gastrointestinal adverse events occurred in 4.4% of the hypofractionated radiotherapy group vs 3.2% of the conventionally fractionated radiotherapy group (relative risk [RR] = 1.39, 95% CI = 0.75–2.55). Late grade ≥ 3 genitourinary adverse events occurred in 4.2% of the hypofractionated radiotherapy group vs 3.4% of the conventionally fractionated radiotherapy group (RR = 1.26, 95% CI = 0.69–2.30).
The investigators concluded, “Long-term disease-free survival is noninferior with hypofractionated radiotherapy compared with conventionally fractionated radiotherapy. Biochemical failure is less with hypofractionated radiotherapy. No significant differences in late grade ≥ 3 gastrointestinal/genitourinary adverse events were observed between assignments.”
Dr. Lee, of Duke University Medical Center, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by grants from the National Cancer Institute. For full disclosures of the study authors, visit ascopubs.org.