Stereotactic body radiotherapy induced high rates of biochemical control and low rates of severe toxicity among men with low- or intermediate-risk prostate cancer, according to results of a retrospective study published in JAMA Oncology.
The results suggest that SBRT, which cuts treatment duration to 4 or 5 days, should be considered a standard option for these men.
“Most men with low- or intermediate-risk prostate cancer undergo conventional radiation, which requires them to come in daily for treatment and takes an average of 9 weeks to complete,” Amar Kishan, MD, assistant professor of radiation oncology at David Geffen School of Medicine at University of California, Los Angeles, and researcher at UCLA Jonsson Comprehensive Cancer Center, said in a press release. “That can be very burdensome on a patient and be a huge interruption on their life. With the improvements being made to modern technology, we’ve found that stereotactic body radiotherapy ... can safely and effectively be done in a much shorter time frame without additional toxicity or compromising any chance of a cure.”
Researchers analyzed data on 2,142 men (mean age, 67.9 years) with low-risk (n = 1,185), favorable intermediate-risk (n = 692) or unfavorable intermediate-risk (265) prostate cancer enrolled in 12 different phase 2 trials of SBRT between 2000 and 2012.
Median follow-up after treatment was 6.9 years (interquartile range, 4.9-8.1).
Results showed 7-year cumulative rates of biochemical recurrence of 4.5% (95% CI, 3.2-5.8) for low-risk disease, 8.6% (95% CI, 6.2-11) for favorable intermediate-risk disease, 14.9% (95% CI, 9.5-20.2) for unfavorable intermediate-risk disease, and 10.2% (95% CI, 8-12.5) for all intermediate-risk disease. These rates appeared similar to those of more conventional types of radiation.
Acute grade 3 or higher genitourinary toxic events occurred in 13 men. Gastrointestinal toxic events occurred in two men.
Researchers observed 7-year cumulative incidences of 2.4% (95% CI, 1.8-3.2) for late grade 3 or higher genitourinary toxic events and 0.4% (95% CI, 0.2-0.8) for late grade 3 or higher GI toxic events.
Possible selection bias related to enrollment, lack of a comparator arm and the inclusion of only physician-scored toxic events served as limitations to this study.
“What is remarkable about this very large study is how favorably stereotactic body radiotherapy compares to all other forms of radiation treatments, both in terms of effectiveness and side effects,” Christopher King, MD, professor of radiation oncology and scientist at UCLA Jonsson Comprehensive Cancer Center, said in a press release. “With such long-term follow-up data, we can now offer this approach to patients with full confidence.” – by John DeRosier
Disclosures: Kishan reports honoraria from Varian Medical Systems Inc. and ViewRay Inc. and an advisory board role with Janssen Pharmaceuticals. King reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.