RT with STAD does not improve overall survival, but shows improvements in several clinical outcomes for men with intermediate-risk PC

2 May 2023
RT with STAD does not improve overall survival, but shows improvements in several clinical outcomes for men with intermediate-risk PC

Results from the phase 3 NRG Oncology RTOG 0815 clinical study comparing dose-escalated radiotherapy (RT) alone to dose-escalated RT with short-term androgen deprivation (STAD) did not meet its primary endpoint of improving overall survival for men with intermediate-risk prostate cancer through the addition of STAD.

Although this study did not meet its primary aim, the addition of STAD to dose-escalated RT was associated with improvements in rates of biochemical failure, distant metastases, and prostate cancer-specific mortality. These results were recently published in the Journal of Clinical Oncology.

“While NRG-RTOG 0815 was able to demonstrate an improvement in some other clinical outcomes for this patient population, it is important to note that these improvements need to be weighed against the increased risk of adverse advents discovered on this trial with the addition of STAD which have the potential to negatively impact patients’ quality of life,” stated Daniel J. Krauss, MD, of the William Beaumont Hospital, Oakland University School of Medicine, and the lead author of the NRG-RTOG 0815 manuscript.

 “These impacts were prospectively quantified in an accompanying patient-reported quality of life study led by Dr. Ben Movsas, which will contribute greatly to patients’ ability to make informed decisions regarding whether or not to add STAD to their radiation treatment.”

NRG-RTOG 0815 accrued 1,492 patients with intermediate-risk prostate cancer and randomly assigned patients to receive either dose-escalated RT alone (external beam RT to 79.2 Gy, or external beam to 45 Gy with brachytherapy boost) or dose-escalated RT with 6 months of STAD with LHRH agonist/antagonist therapy plus anti-androgen.

At the median follow-up of 6.3 years, 5-year overall survival rates were 90% for Arm 1 versus 91% in Arm 2 [HR 0.85 (95% CI 0.65-1.11); p=0.22]. The addition of STAD in Arm 2 resulted in reduced PSA failure (HR 0.52, p < 0.001), distant metastasis (HR 0.25, p < 0.001), prostate cancer-specific mortality (HR 0.10, p = 0.007), and salvage therapy use (HR 0.62, p = 0.025).

Acute grade three or greater adverse events occurred in 2% of patients in Arm 1 and 12% of patients in Arm 2 (p<0.001). The cumulative incidence of late grade > 3 adverse events by 10 years was 16% in Arm 1 and 17% in Arm 2 (p=0.27). 

“Further research is ongoing to better identify subsets of these patients who may be able to reduce their risk of metastatic disease utilizing ADT without the toxicity reflected in this trial data,” Dr. Krauss added.

Supported by grants UG1CA189867 (NCORP), U10CA180868 (NRG Operations), U24CA180803 (IROC), and U10CA180822 (SDMC) from the National Cancer Institute (NCI).

Source: NRG Oncology