A definitive radiotherapy dose for localized prostate cancer can be safely administered using high-dose rate brachytherapy as a single outpatient procedure.
A definitive radiotherapy dose for localized prostate cancer can be safely administered using high-dose rate (HDR) brachytherapy as a single, outpatient, minimally-invasive procedure, according to the results of a prospective, nonrandomized clinical trial published recently in the International Journal of Radiation Oncology, Biology, and Physics (2017; 97:98-106).
Brachytherapy has long been an accepted local therapy for prostate cancer, according to first author Daniel J. Krauss, MD, of Oakland University William Beaumont School of Medicine, Royal Oak, MI.
“Permanent-seed, or low-dose-rate brachytherapy has historically been the more commonly administered treatment and has the advantage of being delivered in a single outpatient surgery, but patients are required to manage the responsibility and inconvenience of carrying radioactive material in their pelvis for several months following the procedure. HDR brachytherapy has a couple of advantages over permanent-seed brachytherapy, including the fact that the patient is not radioactive following the procedure as well as suggestion of reduced rectal toxicity,” Dr. Krauss told Urology Times.
HDR may also be preferred because physicians maintain more control over dose deposition in the prostate because the entire treatment is delivered under his/her direct control, along with theoretical biologic benefit of large, fractional dose delivery felt to be advantageous in the treatment of prostate cancer, Dr. Krauss explained. However, a drawback of HDR brachytherapy, historically, has been the complexity of its administration. Namely, HDR is typically administered in multiple treatment fractions, frequently requiring multiple invasive procedures to complete an entire course of treatment.
“By administering the entire dose in a single-treatment fraction, efficiency is maximized, cost is minimized, and risk to the patient reduced through fewer invasive procedures and minimal exposure to anesthesia,” Dr. Krauss said.
This trial evaluated the use of 19-Gy, single fraction HDR brachytherapy for men with low- and intermediate-risk prostate cancer. The authors enrolled 58 patients; eligible patients had a tumor stage less than T2a, PSA level of 15 ng/mL or less, and a Gleason score of 7 or less. The median age of patients was 61.4 years. Patients underwent transrectal ultrasound-guided transperineal implantation of the prostate, followed by a single-fraction HDR brachytherapy.
According to Dr. Krauss, the main finding of the study was the near-total absence of serious, chronic urinary or rectal toxicity.
With a median of 3 years’ follow-up, the rate of acute and chronic grade 2 genitourinary toxicity was 12.1% and 10.3%, respectively. There were no grade 3 urinary toxicities, and no patients experienced acute rectal toxicity of grade 2 or higher. Only two patients experienced grade 2 or higher chronic gastrointestinal toxicity. One patient experienced a transient episode of grade 2 proctitis and one patient developed a late episode of grade 3 diarrhea, which Dr. Krauss said was likely unrelated to the radiation treatment.
Three patients in the trial had biochemical failure, yielding a 3-year estimated biochemical control rate of 93.2% (95% CI, 79.8%-97.9%).
“While preliminary tumor control rates were promising, further follow-up is necessary to ensure that they compare favorably to previously studied HDR dosing regimens, and additional study is warranted to determine the optimal single-fraction HDR brachytherapy prescription dose and treatment technique,” Dr. Krauss said.
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