Total Androgen Suppression with Dose-Escalated Radiotherapy Does Not Improve Overall Survival in Men with Intermediate-Risk Prostate Cancer: Results Highlight Need for Biomarker Studies
October 25, 2021
In the NRG Oncology clinical trial NRG-RTOG 0815 comparing dose escalated radiotherapy (RT) in combination with short-term androgen suppression (ADT) to dose escalated RT alone for intermediate-risk prostate cancer patients, the addition of ADT did not improve overall survival results as hypothesized by researchers. These results were presented during the Plenary Session of the American Society for Radiation Oncology’s (ASTRO) Annual Meeting in October 2021.
“While we did not demonstrate an overall survival benefit for the addition of androgen suppression to dose-escalated radiotherapy, the findings that the addition of ADT did reduce rates of biochemical failure and distant metastases highlight a crucial need for future studies, especially in the areas of advanced imaging and biomarker identification, that can optimally identify subsets of intermediate risk prostate cancer patients that are most likely to benefit from this intervention,” stated Daniel J. Krauss, MD, of William Beaumont Hospital and the Lead Author of the NRG-RTOG 0815 abstract. “The next generation of prostate cancer radiotherapy studies are, in fact, designed to incorporate molecular biomarker characterization directly into the protocol randomization structure, a critical step that will maximize the chances of accurately identifying patients who will benefit from treatment intensification.”
The Phase III NRG-RTOG 0815 trial accrued and randomized 1,538 patients, of which 1,492 were eligible, with 750 patients assigned to treatment with dose-escalated radiotherapy alone (arm 1) and 742 assigned to treatment with the same radiotherapy plus 6 months of total androgen suppression (arm 2). Patients were stratified by risk factors, comorbidity status, and radiotherapy modality prior to randomization. Radiotherapy options included external beam radiotherapy (EBRT) alone to a total dose of 79.2 Gy or EBRT (45 Gy) combined with low-dose rate or high-dose rate brachytherapy boost.
Trial results did not indicate an improvement in overall survival rates for patients, but results showed clinically significant improvements in secondary endpoints including rates of distant metastases, deaths due to prostate cancer, and PSA failure.
At a mean follow up of 6.2 years, 219 deaths had occurred, 119 in treatment arm 1 and 100 in treatment arm 2, yielding 5-year overall survival estimates of 90% for Arm 1 and 91% in Arm 2 [HR 0.85 (95% CI 0.65-1.11); p=0.22]. A total of 193 patients experienced PSA failure: 125 in Arm 1 and 68 in Arm 2 [HR 0.52 (0.39-0.70); p<0.001], and 35 patients developed distant metastases: 28 in Arm 1 and 7 in Arm 2 [HR 0.25 (0.11-0.57); p<0.001]. Eleven deaths were attributed to prostate cancer: 10 in Arm 1 and 1 in Arm 2 [HR 0.10 (0.01-0.80); p=0.007]. A total of 103 patients experienced acute grade 3 or greater adverse events: 17 (2.3%) in Arm 1 and 86 (11.9%) in Arm 2 (p<0.001). The cumulative incidence of late grade 3 or greater adverse events by 10 years was similar in the two arms: 16.2% in Arm 1 and 17.5% in Arm 2 (p=0.27).
This project was supported by grants UG1CA189867 (NCORP), U10CA180868 (NRG Oncology Operations), U24CA180803 (IROC) from the National Cancer Institute (NCI), part of National Institutes of Health. This project was led by NRG Oncology with participation of other NCI funded network groups.
Krauss DJ, Karrison TG, Martinez AA, Morton G, Yan D, Bruner DW, Movsas B, Elshaikh M, Citrin D, Hershatter B, Michalski JM, Efstathiou JA, Currey A, Kavadi VS, Cury FL, Lock M, Raben Rodgers J, Sandler HM. (2021, October). Dose Escalated Radiotherapy Alone or in Combination with Short-Term Androgen Suppression for Intermediate Risk Prostate Cancer: Outcomes from the NRG Oncology/RTOG 0815 Randomized Trial. Paper presented at the annual meeting of the American Society for Radiation Oncology. Chicago, IL and hybrid virtual meeting platform.
About NRG Oncology
NRG Oncology conducts practice-changing, multi-institutional clinical and translational research to improve the lives of patients with cancer. Founded in 2012, NRG Oncology is a Pennsylvania-based nonprofit corporation that integrates the research of the legacy National Surgical Adjuvant Breast and Bowel Project (NSABP), Radiation Therapy Oncology Group (RTOG), and Gynecologic Oncology Group (GOG) programs. The research network seeks to carry out clinical trials with emphases on gender-specific malignancies, including gynecologic, breast, and prostate cancers, and on localized or locally advanced cancers of all types. NRG Oncology’s extensive research organization comprises multidisciplinary investigators, including medical oncologists, radiation oncologists, surgeons, physicists, pathologists, and statisticians, and encompasses more than 1,300 research sites located world-wide with predominance in the United States and Canada. NRG Oncology is supported primarily through grants from the National Cancer Institute (NCI) and is one of five research groups in the NCI’s National Clinical Trials Network.