A longer course of androgen deprivation therapy (ADT) does not improve outcomes in patients with localized, high-risk prostate cancer receiving I-125 brachytherapy and external beam radiotherapy (EBRT), according to data presented at the 2023 ASCO Genitourinary Cancers Symposium.
Patients who received 30 months of ADT saw no benefits in progression or survival outcomes when compared with patients who received 6 months of ADT.
These results suggest that ultra-high radiation doses can be combined with a shorter course of ADT without decreasing survival, according to study presenter Atsunori Yorozu, MD, PhD, of the National Hospital Organization Tokyo Medical Center in Japan, and colleagues.
For this phase 3 trial, Dr Yorozu and colleagues evaluated 332 patients with localized, high-risk prostate cancer. At baseline, the patients’ median age was 70 years (range, 50-79 years), the median prostate-specific antigen level was 16.2 ng/mL (range, 3-182 ng/mL), and 43% of patients had multiple high-risk features.
All patients received 6 months of ADT combined with I-125 brachytherapy (110 Gy), followed by EBRT (45 Gy in 25 fractions). Patients were then randomly assigned to either no further treatment (short-term treatment arm; n=165) or an additional 24 months of adjuvant ADT (long-term treatment arm; n=167). The median follow-up was 9.3 and 9.0 years, respectively.
At 9 years, the cumulative incidence of biochemical progression was 10.4% in the short-term arm and 9.5% in the long-term arm (hazard ratio [HR], 0.85; 95% CI, 0.44-1.66; P =.65).
The cumulative incidence of biochemical progression or death at 9 years was 12.4% in the short-term arm and 14.0% in the long-term arm (HR, 1.05; 95% CI, 0.60-1.84; P =.86).
Similarly, there was no significant difference between the arms for other endpoints, including clinical progression, metastasis, salvage treatment, disease-specific survival, overall survival, and grade 3 or higher adverse events (AEs).
The rate of grade 3 endocrine-related AEs was 0.6% in the short-term arm and 1.8% in the long-term arm (P =.31). The rate of grade 3 radiation-related AEs was 1.2% and 0.6%, respectively (P =.93). There were no grade 4 or higher endocrine- or radiation-related AEs in either arm.
Disclosures: This research was supported by AstraZeneca and Nihon-Mediphysics. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.
Yorozu A, Namiki M, Saito S, et al. Results of a multicenter, randomized, phase 3 trial of trimodality therapy with I-125 brachytherapy, external beam radiation therapy, and long- versus short-term androgen deprivation therapy for localized high-risk prostate cancer (TRIP/TRIGU0907). ASCO GU 2023. February 16-18, 2023. Abstract 305.
This article originally appeared on Cancer Therapy Advisor