In a long-term follow-up of the phase III MD Anderson dose-escalated, hypofractionated prostate radiation study reported in the Journal of Clinical Oncology, Hassanzadeh et al compared hypofractionated intensity-modulated radiation therapy (HIMRT) vs conventionally fractionated intensity-modulated radiation therapy (CIMRT) in patients with predominantly low- or intermediate-risk localized prostate cancer.
Study Details
In the trial, 206 evaluable patients were randomly assigned between January 2001 and January 2010 to receive HIMRT at 72 Gy in 2.4-Gy fractions (n = 104) or CIMRT at 75.6 Gy in 1.8-Gy fractions (n = 102). The primary outcome measure was treatment failure defined as prostate-specific antigen failure or initiation of salvage therapy. In the initial report from the trial, HIMRT was associated with a significant benefit in treatment failure. The current report presents 13-year outcomes of the trial.
Key Findings
At a median follow-up of 13.2 years (interquartile range = 8.8–15.9 years), treatment failure occurred less frequently in the HIMRT group (n = 13) vs the CIMRT group (n = 22), with the difference no longer being significant (P = .08). The failure rate at 10 years was 11% (95% confidence interval [CI] = 5.5%–18.1%) in the HIMRT group vs 21% (95% CI = 13%–30.5%) in the CIMRT group.
No significant difference in overall survival was observed between the HIMRT group and the CIMRT group, with 15-year rates of 87% vs 75% (P = .08). Distant metastases occurred in six patients in the HIMRT group vs two in the CIMRT group (P = .2).
For the HIMRT group vs the CIMRT group, there were no significant differences in late grade ≥ 2 gastrointestinal or genitourinary toxicity; rates at 10 years were 10% vs 4% (P = .09) and 26% vs 23% (P = .5), respectively.
The investigators concluded: “In this randomized clinical trial with a median follow-up of 13 years, men with localized, predominantly favorable intermediate-risk prostate cancer who received dose-escalated, hypofractionated RT had reduced treatment failure, although this did not meet statistical significance.”
Comron Hassanzadeh, MD, MPH, of the Department of Genitourinary Radiation Oncology, The University of Texas MD Anderson Cancer Center, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by a grant from the National Cancer Institute. For full disclosures of all study authors, visit the Journal of Clinical Oncology.
