Under the RADAR.

Top Line: Ahh TROG RADAR, the trial that keeps giving.

The Study: While its main goal was to determine if 18 versus 6 months of androgen deprivation therapy (ADT) reduced distant relapse, a variety of radiation dosing schemes were allowed—providing the opportunity to explore differences in outcome based on radiation dose. The schemes (all at 2 Gy per fraction) were declared up-front and included 66 Gy, 70 Gy, and 74 Gy total or 46 Gy external beam with a 6.5 Gy x 3 = 19.5 Gy high-dose rate (HDR) boost. It looks like the 10 year analysis of outcomes are going to fuel the ongoing debate of brachytherapy for high-risk disease. Compared to the 40% of men who received 70 Gy, the 20% who received HDR boost had significantly lower rates of distant progression and prostate cancer mortality. Compared to those who received 74 Gy, these outcomes were only numerically better. Importantly, they found no apparent interaction between ADT and radiation dose with respect to distant relapse. The benefit of 18 months ADT was independent of radiation dose—even in the setting of HDR.

TBL: The distant progression benefit of longer ADT was independent of radiation dose in the TROG RADAR trial, and patients who received non-randomized HDR boost achieved better clinical outcomes. | Joseph, Int J Radiat Oncol Biol Phys 2020