The long-term follow up of the NRG Oncology trial RTOG 9408, studying the addition of short-term androgen-deprivation therapy (ADT) to radiotherapy (RT) for men with early, localized prostate adenocarcinoma, indicated that RT combined with ADT is superior to RT alone for overall survival (OS) up to 10.4 years following treatment. However, when researchers assessed these results up to 18 years, the benefits of adding ADT to RT dissipated. The results were presented at the American Society for Radiation Oncology’s Annual Meeting in San Antonio, TX on October 22, 2018 during the Genitourinary 2: Long-Term Updates of Prospective Prostate Cancer Clinical Trials session. The study was also awarded a “Best of ASTRO” designation.
The primary aim of NRG-RTOG 9408 was to determine if the addition of four months of ADT before and during RT would improve the overall survival of men with prostate adenocarcinoma. Secondary objectives included determining the difference in disease-specific mortality (DSM), biochemical failure (BF), incidence of distant metastases (DM) and local progression (LP). 1974 men were randomly assigned to either receive RT alone (990 patients) or RT plus four months of ADT (984 patients).
“After concluding that the addition of ADT did provide benefit for both primary and secondary aims, we continued to survey results up to 18 years from treatment. The median follow up for surviving patients was 14.8 years. Our study team noticed that overall survival data began to favor the radiotherapy alone arm over the experimental, androgen-deprivation therapy arm following the first ten years after treatment. However, disease-specific mortality, biochemical failure, incidence of distant metastases and local progression continued to show long-term benefit,” stated Dr. Christopher U. Jones of Sutter Cancer Centers and Lead Author of NRG-RTOG 9408.
The incidence of late grade 3, 4, and 5 genitourinary and gastrointestinal toxicities was low and similar between the ADT and RT arms.