One is the loneliest number.

Earlier this year, a randomized phase 2 trial showed that single-fraction HDR monotherapy (19 Gy x 1) had a significantly higher rate of local failure (29% vs 3% at 5 years) than 13.5 Gy x 2 for men with low and intermediate risk prostate cancer. This outcome left many scratching their heads, and leads one to wonder if dose escalation to the dominant intraprostatic lesion (DIL) could improve outcomes. This study compares the outcomes of two different trials: one that gave 19 Gy x 1 to the whole prostate and another that also gave an MRI-guided boost of 23 Gy to the DIL. Even though toxicity remained low with the dose escalated boost, biochemical failure at 5 years was still > 30%. TBL: Dose escalation with a focal boost up to 23 Gy does not improve the disappointingly high rate of biochemical failure with single-fraction HDR monotherapy. | Alayed, Radiother Oncol 2020