The minimum duration of androgen deprivation therapy (ADT) that provides a distant metastasis-free survival benefit in patients with high-risk prostate cancer is more than 18 months for those receiving external beam radiotherapy (EBRT) and 18 months or possibly less for those receiving EBRT with a brachytherapy boost (EBRT+BT), investigators reported in JAMA Oncology.
For the longest distant metastasis-free survival, a natural cubic spline analysis identified a minimum ADT duration of 26.3 months for EBRT and 12 months for EBRT+BT, Amar U. Kishan, MD, of the University of California, Los Angeles, and colleagues reported.
Current National Comprehensive Cancer Network guidelines recommend 18 to 36 months of ADT with EBRT and 12 months of ADT with EBRT+BT for high-risk disease. In real-world settings, men are receiving considerably shorter durations of ADT than indicated.
For the study, the investigators pooled and analyzed data from across 3 cohorts totaling 3410 men. In a multicenter retrospective study from 2000-2013, a total of 1827 patients were treated with EBRT and 1108 patients received EBRT+BT. In the 2003-2007 RADAR (Randomized Androgen Deprivation and Radiotherapy) trial, 181 received EBRT and 203 received EBRT+BT. In the 2005-2010 DART (Deprivación Androgénica y RadioTerapía) trial, 91 patients were treated with EBRT. ADT duration and high-dose (74 Gy or higher) radiation therapy was determined by the physician or randomization.
In RADAR, prolonged ADT significantly improved metastasis-free survival by 44% for patients receiving EBRT+BT but showed no benefit for patients receiving EBRT only. In DART, patients receiving 28 months of ADT and EBRT alone had a significant 63% improvement in metastasis-free survival.
“The findings of the present study raise the possibility that for patients receiving EBRT, 18 months of ADT may be inferior to longer durations,” Dr Kishan’s team wrote. ADT durations of less than 18 months may be sufficient for patients receiving EBRT+BT, according to the investigators.
Disclosure: Some [or one] study author(s) declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
Kishan AU, Steigler A, Denham JW, et al. Interplay between duration of androgen deprivation therapy and external beam radiotherapy with or without a brachytherapy boost for optimal treatment of high-risk prostate cancer: a patient-level data analysis of 3 cohorts. JAMA Oncol. Published online January 20, 2022. doi:10.1001/jamaoncol.2021.6871