Adding external-beam radiation to brachytherapy does not improve 5-year freedom from progression (FFP) for men with intermediate-risk prostate cancer, but it does increase treatment toxicity.
The study included patients with T1c–T2b prostate cancer. The patients' Zubrod performance scale score was 0–1, they either had a Gleason Score of 2–6 and a prostate-specific antigen (PSA) level of 10–20 or a Gleason Score or 7 and a PSA level of less than 10.
In one arm of the randomized trial, 292 patients received prostate brachytherapy alone (145 Gy if iodine-125, 125 Gy if palladium-103).
In the other arm, 287 received external-beam radiotherapy (45 Gy in 25 fractions) to the prostate and seminal vesicles followed by prostate brachytherapy (110 Gy if iodine-125, 100 Gy if palladium-103).
The 5-year FFP, using the American Society for Therapeutic Radiology and Oncology definition, was 85.6% with the combination, vs 82.7% with brachytherapy alone (odds ratio [OR], 0.80; P = .18).
The 5-year FFP, using the Phoenix definition, was 88% with the combination, compared with 85.5% with brachytherapy alone (OR, 0.80; P = .19).
Adding external-beam radiation also did not yield an improvement in secondary endpoints of local progression, distant metastases, or disease-specific mortality.
There was no difference in genitourinary or gastrointestinal acute toxicity rates, but the 5-year cumulative incidence for late-grade 3+ toxicity was more than twofold higher with the combination (8.2% vs 3.8%; P = .006).
"[Brachytherapy] alone can be considered a standard of care for men with intermediate-risk prostate cancer," the authors concluded.
The study was led by Jeff Michalski, MD, of Washington University in St. Louis and was published June 14 in the Journal of Clinical Oncology.
Radiation was limited to the prostate and seminal vesicles; failure to cover pelvic lymph nodes of patients with occult nodal metastases could have contributed to the lack of benefit with radiation.
Some of the radiation procedures in the trial may not reflect contemporary methods and could have contributed to differences in late toxicity.
The work was funded by the National Cancer Institute.
Several investigators have industry ties, including Michalski, who reported receiving consulting and/or speakers' fees from Novartis and Boston Scientific.
M. Alexander Otto is a physician assistant with a master's degree in medical science and a journalism degree from Newhouse. He is an award-winning medical journalist who worked for several major news outlets before joining Medscape. Alex is also an MIT Knight Science Journalism fellow. Email: email@example.com.
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Cite this: Adding Radiation for Intermediate-Risk Prostate Cancer? - Medscape - Jun 23, 2023.